rat
rat — noun
1. A small furry animal with a pointed nose, a hairless tail, and strong front teet
A small furry animal with a pointed nose, a hairless tail, and strong front teeth. These animals grow bigger than common mice and often live in or near human homes, where they may be treated as pests or kept as pets.
Hana saw a large rat run across the kitchen floor and screamed.
Ritu keeps two pet rats in a glass cage with wood shavings and a wheel.
collocation: pet rat
In the old warehouse, rats had chewed through several bags of flour.
The landlord called an exterminator because the apartment building had a serious rat problem.
A brown rat can squeeze through a hole no bigger than a coin.
常見錯誤
2. An insulting word for someone who cheats, lies to, or leaves behind the people w
An insulting word for someone who cheats, lies to, or leaves behind the people who trusted them, such as friends or work partners.
Bilal called his former business partner a dirty rat after losing all his savings.
collocation: dirty rat
Élise realized a friend had turned rat when the police arrived at her door.
phrasal: turn rat
The newspaper described the mayor as a rat who had tricked the voters for years.
Tendai warned his younger brother not to trust that man, calling him a lying rat.
- traitor
more general; can refer to betraying a country, group, or cause
- informer
neutral or negative; specifically refers to someone who gives information to authorities
- backstabber
suggests betrayal through secret or dishonest actions
- snitch
slang; specifically refers to someone who tells on others, especially to police
- ally
someone who supports and stands by you
- loyal friend
someone who stays faithful even in difficult situations
用法筆記
Strongly offensive. Avoid using in polite or professional conversation. Often appears in fixed name-calling phrases such as 'dirty rat' or 'lying rat.'
3. A fast medical test that checks for a specific virus or bacteria by looking for
A fast medical test that checks for a specific virus or bacteria by looking for proteins called antigens on a small sample, usually taken from the nose or throat.
The school required a negative RAT result before students could return to class.
abbreviation: RAT stands for rapid antigen test
Anong took a RAT at home and was relieved to see only one line appear.
Many pharmacies sold RAT kits so people could check themselves before visiting family.
The nurse said a RAT gives results in fifteen minutes, faster than a lab test.
- rapid test
shorter form, less specific about the type of test
- PCR test
a different type of test that looks for genetic material and takes longer to process
用法筆記
Almost always written in all-caps (RAT) when used as an abbreviation. Spoken as separate letters (R-A-T), not as the word 'rat.' Common in public health and medical contexts, especially during the COVID-19 pandemic.
4. A small device with spinning blades that drops out of an aircraft when the main
A small device with spinning blades that drops out of an aircraft when the main engines fail, using the flow of outside air to produce emergency electricity or power for the control systems.
When both engines shut down, the RAT deployed automatically beneath the aircraft's wing.
passive: RAT deployed
The pilot checked that the RAT had enough hydraulic pressure to move the control surfaces.
During the emergency landing, the RAT provided the power needed to steer the plane safely.
Engineers designed the RAT to pop out automatically when the main power supply fails.
用法筆記
Almost always written as the abbreviation RAT in aviation contexts. Spoken as 'R-A-T,' not as 'rat.' This term is extremely specialized and appears almost exclusively in aircraft maintenance manuals and pilot training materials.
rat — verb
1. To secretly tell a person in authority, such as the police or a teacher, about s
To secretly tell a person in authority, such as the police or a teacher, about something wrong or illegal that a friend or group member has done.
Nicholas refused to rat on his classmates even though the principal demanded names.
pattern: rat on + someone
Someone ratted Yael out to the manager about the missing inventory.
pattern: rat + someone + out
Paloma was afraid that her brother would rat her out for sneaking out after midnight.
The gang member who ratted on his partners received a new identity from the police.
- cover for
to protect someone by hiding their actions or mistakes
文法句型
rat on + someone
rat + someone + out
用法筆記
Almost always used with the particle 'on' (rat on someone) or 'out' (rat someone out). Without these particles, 'rat' as a verb is very rare and sounds dated. 'Rat someone out' is more common in American English; 'rat on someone' is common in both British and American English.
常見錯誤
2. To try to find and kill or capture rats, often using a trained dog or a mechanic
To try to find and kill or capture rats, often using a trained dog or a mechanical trap, so that their population stays under control.
The farmer's terrier has been ratting in the barn since dawn.
present perfect continuous: has been ratting
Nellie trained her small dog to rat in the garden shed after dark.
Some people still use ferrets to rat in old warehouses and grain stores.
The old cat from next door used to rat in our backyard every night.
- hunt rats
more literal and transparent; 'rat' used as a regular transitive verb
用法筆記
This sense is uncommon in modern everyday English. It appears mainly in rural contexts or discussions of traditional pest control with working dogs. The -ing form 'ratting' is more common than the base form.
3. To take the job of a worker who is on strike, or to bring in outside workers to
To take the job of a worker who is on strike, or to bring in outside workers to replace striking employees, so that the company can keep operating.
The factory hired temporary staff to rat during the month-long workers' strike.
domain: labor relations
Ramón refused to rat during the strike even though he needed the money badly.
Union members stood outside the gate, shouting at the drivers who were ratting.
The newspaper reported that several truckers had chosen to rat rather than lose their jobs.
- scab
more common than 'rat' in this sense; also a highly offensive term in labor contexts
- cross the picket line
describes the action of working while other employees are on strike
用法筆記
Strongly negative within labor-union contexts. Calling someone a 'rat' in this sense implies they have betrayed their fellow workers for personal gain. This usage is almost entirely restricted to discussions of organized labor and strikes.