under
under — adjective
1. positioned at a lower level directly beneath another thing, often serving as the
positioned at a lower level directly beneath another thing, often serving as the hidden or supporting part of something.
Dahlia peeled away the under layer of old paint to reveal the original wood beneath.
attributive: under + noun describing position
After moving the shelf, Marta ran her hand along its under surface to check for cracks.
under + surface: 'under' before noun, not after verb
The under side of the stone bridge near the park was thick with green moss after the wet spring.
A small tear in the under panel of Zayd's tent let rainwater drip onto his sleeping bag.
Rust had formed on the under panel of the car door near the hinge.
文法句型
under + noun
用法筆記
Always placed before a noun (attributive position). Unlike the preposition 'under', the adjective cannot follow a linking verb — you cannot say 'the layer is under' to mean it is the lower one.
常見錯誤
2. turned or pointing toward the ground or the lower side of something, rather than
turned or pointing toward the ground or the lower side of something, rather than upward.
Christopher bit his under lip nervously while waiting for the test results.
under + lip = the lower edge of the mouth
A small green frog sat on a lily pad, its under jaw pulsing gently as it waited for a fly.
Hiro noticed a small cut on the under side of the dog's front paw.
The under parts of the old eagle's wings were nearly bare, with most feathers gone after years of flying.
- upper
positioned above or facing upward
文法句型
under + noun
用法筆記
Most commonly used with body parts (lip, jaw, side) or parts of animals and objects to describe their downward-facing surface.
常見錯誤
3. holding a position or having a level of authority that is below someone else in
holding a position or having a level of authority that is below someone else in an organisation or group.
The under officers reported directly to the captain during the training exercise.
under + officer = subordinate rank in a hierarchy
Kemi trains new under staff at the regional office, showing them how to use the company software.
Under managers at the city bank must ask senior directors for approval before they change any budgets.
The under chief at the fire station managed daily training while the chief planned next year's budget.
- subordinate
more formal, describes the relationship explicitly
- junior
focuses on experience or age rather than position
- lower-ranking
more explicit about the hierarchy level
文法句型
under + noun (job title)
用法筆記
Used in job titles and role descriptions to indicate a position one step below the main role. More formal than 'assistant' or 'deputy'.
常見錯誤
4. at a level of amount, quality, or intensity that is below what is expected, prop
at a level of amount, quality, or intensity that is below what is expected, proper, or acceptable.
The factory ran at under capacity for three months after the power failure.
under + capacity = below maximum possible output
The factory inspector rejected the batch because an under temperature during drying had weakened the material.
Mia complained about the under quality of the fabric after the first wash.
An under supply of clean water created serious problems at the mountain clinic.
- insufficient
more general, also used for abstract quantities
- inadequate
suggests failure to meet a required standard
- below-standard
more explicit but less common as a single word
- above-standard
exceeding expected levels
- adequate
meeting the required level
- sufficient
enough for the purpose
文法句型
under + noun (measurable quality)
用法筆記
Used with nouns that denote measurable qualities (temperature, capacity, supply, quality). Often appears in technical or formal reports. Distinguish from the prefix 'under-' which attaches to verbs (undercooked, underpaid) — the adjective remains a separate word.
常見錯誤
under — adverb
1. in or to a position beneath the surface of water or another substance, so that t
in or to a position beneath the surface of water or another substance, so that the thing is partly or completely covered.
The young seal dove under the icy water and stayed below for nearly two minutes before surfacing.
verb of movement + under for submerging
Christopher pushed the floating leaf under until it was completely wet.
push + under (make something go below surface)
The old wooden boat slowly went under in the cold, dark lake.
Élise held her breath and went under to look for the lost ring.
Nkechi watched the bright orange fish swim under the rock and vanish from her sight.
- up
up describes movement toward or position at a higher point, the opposite of going beneath a surface.
用法筆記
Commonly follows verbs describing downward movement or submerging, such as dive, go, sink, push, and slip.
常見錯誤
under — prefix
1. added to verbs or their past-participle forms to mean 'not enough' or 'less than
added to verbs or their past-participle forms to mean 'not enough' or 'less than what is needed' — for example, food that is undercooked has not been cooked long enough, or a worker who is underpaid receives too little money for their work.
Xiu put the undercooked chicken back in the oven for ten more minutes.
undercooked = not cooked enough
Tara felt underpaid for the long hours she worked at the office.
underpaid = paid too little
The company underestimated how much the new building would cost to finish.
Many children in poor rural areas are undernourished because their families cannot afford enough food.
Ife's math teacher said he was underachieving — he scored low on tests despite finishing all his homework correctly.
- insufficiently
adverb used in more formal writing; under- is a prefix, not a separate word
- inadequately
stronger formality; used for serious shortcomings
- over-
the opposite prefix meaning 'too much', as in overpay, overcook
文法句型
under- + [verb]
under- + [past participle]
用法筆記
Frequently attaches to verbs (undercook, underpay, underestimate, underachieve) and their past-participle forms used as adjectives (undercooked, underpaid, undernourished). This prefix does not combine freely with all verbs — for instance, 'undereat' is very uncommon, while its opposite 'overeat' is common.
常見錯誤
2. added to nouns or verbs to mean 'below' or 'beneath something' — for example, an
added to nouns or verbs to mean 'below' or 'beneath something' — for example, an underground train runs below the ground, and to underline a word means to draw a line underneath it.
The subway train runs on underground tracks beneath the busiest streets in the city.
underground = below the ground
The teacher asked Quinn to underline the most important sentence in each paragraph.
underline = draw a line below
The navy submarine traveled underwater for three months without once coming up to the surface for air.
The dog escaped by digging an underground tunnel right under the wooden fence.
The doctor examined Léa's red underarm and said the mild rash would clear up within a week.
文法句型
under- + [noun]
under- + [verb]
用法筆記
Attaches to nouns (ground, water, arm, belly) to form adjectives or nouns describing a physical position lower than something else. The meaning is literal and spatial — compare with sense 1 (NOT ENOUGH), where the prefix indicates a shortfall or deficiency rather than physical position.
常見錯誤
under — preposition
1. in a position directly below something, often with the upper thing hiding, prote
in a position directly below something, often with the upper thing hiding, protecting, or touching the lower thing
The cat was sleeping under the kitchen table while Ayana made dinner.
under + noun phrase for location
Trang found her keys under a pile of old newspapers on the desk.
The children hid under their beds during the thunderstorm.
Takeshi keeps a small safe under the floorboards in his study.
We sat under a large umbrella to stay out of the hot sun.
文法句型
under + noun phrase
常見錯誤
2. describing a stretch of land that has a single crop or native vegetation coverin
describing a stretch of land that has a single crop or native vegetation covering its whole surface
The field was under wheat, stretching all the way to the river.
under + crop type for land usage
The entire valley floor near the village is under rice paddies that stretch from the road to the hills.
Ten acres of the farm are under organic vegetables this year.
Every spring the hills behind the village are under purple wildflowers that bloom for about three weeks.
- planted with
more active; focuses on the planting action rather than the state
- covered by
broader; can describe any covering, not just plant life
文法句型
under + [type of plant/crop]
用法筆記
Subject is always an area of land (field, valley, hills, acres). The plant or crop name follows immediately — no article before the crop name.
常見錯誤
3. arranged somewhere inside a classification scheme, so someone searching can loca
arranged somewhere inside a classification scheme, so someone searching can locate it by that label in a catalogue, index, or collection
You can find all novels by that author under the letter 'M'.
under + heading for finding in a system
The report is filed under 'Finance' in the office cabinet.
Sofie looked up 'snake bite' under 'First Aid' in the manual.
All the old photographs are organised under different family surnames.
- within
more general; less specific about following a heading
- in the category of
more formal and explicit
文法句型
under + [category/heading/title]
用法筆記
Common in library, computing, and office contexts. The category label is usually a singular noun in quotes or capitalised. 'Filing under' is a frequent fixed expression.
常見錯誤
4. less than a particular number, amount, price, or age — used when the upper limit
less than a particular number, amount, price, or age — used when the upper limit is a precise figure
Children under twelve get a free ticket to the zoo.
under + age for age limit
The whole renovation project cost under five thousand dollars.
Meera finished the ten-kilometer race in under thirty minutes, beating her personal best by two minutes.
In Brazil, nobody under the age of eighteen is permitted to vote in any local or national election.
文法句型
under + [number/amount/age]
用法筆記
Only for quantities that can be counted or measured precisely (age, price, time duration, distance). Not used for abstract comparisons ('under important' ❌ — use 'less important'). 'Under the age of [number]' is a common fixed structure.
常見錯誤
5. within a specific framework of rules, agreements, or external conditions that sh
within a specific framework of rules, agreements, or external conditions that shapes how an action or situation develops — the noun after 'under' names the environment that influences events
The company has been operating under new management since January.
under + management/leadership
Under the current health law in Japan, smoking is banned in all restaurants and office buildings.
The rescue team worked under extremely difficult weather conditions.
Kian agreed to help the team write the report under the condition that his name not appear anywhere in it.
Ignacio felt enormous pressure under the circumstances, having lost three staff members in one week.
- according to
narrower; mainly for rules and agreements, not for circumstances
- during
temporal only; lacks the sense of being affected by the situation
- subject to
more formal; emphasises being bound by conditions
文法句型
under + [condition/law/circumstance]
用法筆記
Distinguish from 'under' sense 9 (controlled by a person/organisation): this sense focuses on situations, rules, or conditions affecting what happens, not direct control by a person or group.
常見錯誤
6. currently being subjected to a particular action or treatment, such as repair, e
currently being subjected to a particular action or treatment, such as repair, examination, discussion, or attack — forming fixed expressions with action nouns
The old bridge is under repair, so drivers need to use a different route.
under repair = being repaired
Several new safety policies for the school are under discussion at the town council meeting this week.
The mayor's decision is under attack from local community leaders.
A proposal to build a new community sports centre is under consideration by the city planning department.
- being + past participle
grammatically equivalent but less concise: 'being discussed' vs 'under discussion'
- undergoing
more formal; can be used more freely with different nouns
文法句型
under + [action noun]
用法筆記
This sense only works with a fixed set of action nouns: attack, consideration, discussion, investigation, repair, construction, threat, review, etc. You cannot freely create new combinations — 'under eating' or 'under building' are not idiomatic. No article is used between 'under' and the noun.
常見錯誤
7. experiencing a specific medical, legal, or supervisory condition that determines
experiencing a specific medical, legal, or supervisory condition that determines how a situation is handled — the noun after 'under' names the treatment or protocol applying to the subject
The surgery was performed under local anesthesia, so the patient stayed awake.
under + medical procedure
Hoa signed the contract under protest, saying she did not agree with the terms.
under + protest (fixed phrase for unwilling compliance)
The children were painting under the careful supervision of their art teacher.
The old building was demolished under a court order after years of legal battles.
Élise completed her training under the guidance of an experienced chef from France.
- subject to
more formal; implies being affected by a rule or condition rather than a state
- undergoing
used only for processes or treatments, not states like protest
文法句型
under + noun phrase
用法筆記
Common with nouns naming a medical, legal, or supervision condition (anesthesia, protest, court order, supervision). The noun phrase names the state or treatment the subject is experiencing.
常見錯誤
8. having a particular idea or belief about something, especially one that may turn
having a particular idea or belief about something, especially one that may turn out to be wrong
The school director was under the impression that all parents had been told about the schedule changes.
under the impression + that-clause
Yan bought the old watch under the illusion it was worth a lot of money.
under the illusion + that-clause (false belief about value)
Shanti was under the mistaken belief that the exam started at ten instead of nine.
Many voters were under the delusion that the new housing policy would fix their rent problems overnight.
Asher left his job under the impression that he would receive a large payment.
- knowing for sure
implies certainty, not a possibly mistaken impression
文法句型
under the impression / illusion / delusion + that-clause
under the mistaken belief + that-clause
用法筆記
Always followed by a that-clause or a noun complement (e.g. 'under the impression that…'). The most common noun in this pattern is 'impression'; 'illusion' suggests a more obviously false belief, while 'delusion' is stronger still and often implies self-deception.
常見錯誤
9. operating with a person, group, or administrative system having direct authority
operating with a person, group, or administrative system having direct authority over you — the noun after 'under' names who or what is in charge
The region has been under military control since the conflict began last year.
under + military control
The new hospital was built under the direction of the Ministry of Health.
under + direction of [institution]
Caleb runs a small company under the overall management of a parent corporation.
Under the current administration in Mexico, small business tax rules have become much more complicated.
The charity operates under strict government rules to make sure all money is used properly.
- governed by
more formal; focuses on legal or political authority
- run by
informal; emphasizes daily operation rather than authority
- independent of
outside the control or authority of
文法句型
under + noun phrase (person, organization, system)
用法筆記
Frequently used with nouns denoting organizations (government, board, management), authority figures (director, chief), and abstract systems (law, constitution, regulations). The sense focuses on hierarchy and compliance rather than physical position.
常見錯誤
10. having received a command or instruction from someone in authority to do somethi
having received a command or instruction from someone in authority to do something
The soldiers were under orders not to leave the base after dark.
under orders + not to (negative command)
Joaquín was under strict instructions to deliver the package before noon the next day.
under instructions + to-infinitive (deadline)
The security guard acted under orders from his supervisor when he asked everyone to leave.
The pilot was under orders to turn the plane around because of the storm ahead.
Rachid's marketing team is under instructions to finish the quarterly financial report by Friday afternoon.
- instructed to
less formal; common in everyday work contexts
- commanded to
stronger, military tone; implies strict authority
- free to
no obligation or command
文法句型
under orders + to-infinitive
under instructions + to-infinitive
用法筆記
Typically followed by a to-infinitive clause specifying the required action. 'Under orders' is more common in military and formal contexts; 'under instructions' is more common in workplace settings. The person giving the order can be stated with 'from': 'under orders from the general'.
常見錯誤
11. operating or identifying yourself with a chosen name, often a false one rather t
operating or identifying yourself with a chosen name, often a false one rather than your real name
The author wrote novels under a pen name so her family would not find out.
under + pen name (publishing)
Christopher checked into the hotel under a false name to avoid the reporters waiting outside.
The spy traveled under a fake passport that identified him as a Canadian businessman.
Pim wrote his political articles under a pseudonym to protect his job at the ministry.
Abigail registered for the online platform under a made-up name for extra privacy and safety.
文法句型
under + a/an + (adjective) + name
用法筆記
The noun phrase after 'under' names the identity being used, typically a pen name, pseudonym, alias, or false name. Common in publishing, entertainment, travel, and online contexts.