index
index — noun
1. an alphabetically ordered section in the final pages of a publication that shows
an alphabetically ordered section in the final pages of a publication that shows the page numbers for topics, names, and subjects discussed throughout the work.
Mark checked the index at the back of the textbook for the page on verbs.
noun + at the back of [a book]
Eve found the entry for 'climate change' in the index of the library book.
The index listed every country mentioned in the history book with a page number.
Daichi used the index to skip straight to the chapter about the French Revolution.
Mert checked the index before buying the cookbook to see if it included curry recipes.
用法筆記
Not the same as a table of contents, which lists chapters in order at the front of a book. An index is alphabetical and appears at the back.
常見錯誤
2. a structured set of records kept in a computer filing system or on physical card
a structured set of records kept in a computer filing system or on physical cards, designed to make retrieval fast.
Ilan searched the computer's file index to find the document from last Tuesday.
computer's file index
Rafael built an index of all the patient records on the hospital database.
The library's card index held information about every book in the building.
Christopher updated the email index so the search tool could find old messages faster.
- database
contains the actual data, while an index points to where the data is
- filing system
less technical; any organized method of storing records
- catalogue
a systematic list of items, often with descriptive details
用法筆記
In computing, an index is a data structure that speeds up searches in a database. In libraries, a physical card index serves a similar purpose.
常見錯誤
3. a set of numbers that shows how the value of a group of items, such as prices or
a set of numbers that shows how the value of a group of items, such as prices or stocks, changes over time and allows comparisons against a standard.
Marco watched the stock market index rise by three percent in one week.
stock market index rises / falls
The consumer price index showed that food costs had gone up by nearly five percent.
Sahil compared the index for housing prices between the years 2010 and 2020.
Élise learned that a country's happiness index depends on many factors beyond income.
用法筆記
Often used in compound noun phrases: 'stock market index', 'consumer price index', 'body mass index'.
常見錯誤
4. a sign or piece of evidence that reveals the strength of a particular condition,
a sign or piece of evidence that reveals the strength of a particular condition, feeling, or quality, providing a clue about a broader situation.
Low attendance at the meeting was an index of how tired the team felt.
be an index of [something]
A child's willingness to share can be an index of their social development.
Doctors use a pain index from one to ten to measure a patient's discomfort.
The number of applicants for a job is often an index of the local economy.
用法筆記
Distinguish from noun sense 3 (COMPARISON SCALE): this sense points to a single observable sign, not a calculated numeric system. Common in academic writing: 'be an index of…'.
常見錯誤
5. a numeral placed slightly above another numeral to show the count of times the l
a numeral placed slightly above another numeral to show the count of times the lower number is used as a factor in multiplication.
In 4³, the small number 3 is the index telling you to multiply 4 three times.
the index in [expression] tells you to multiply [base] [exponent] times
The teacher asked the class to find the index in two to the fifth power.
A high index means the base number gets multiplied by itself many more times.
Eshe learned that the index in 2⁵ tells her to multiply 2 by itself five times.
- exponent
more common term in everyday math for the raised number
- power
often used for the whole operation (e.g., '4 to the power of 3')
- superscript
describes the position of the number, not its mathematical function
用法筆記
In mathematics, 'index' is used interchangeably with 'exponent' or 'power'. The plural is 'indices' (/'ɪndɪsiːz/) in technical contexts, though 'indexes' is also accepted.
index — verb
1. to create an alphabetical list of the topics, names, or subjects in a book, coll
to create an alphabetical list of the topics, names, or subjects in a book, collection, or set of data, or to add information to such a list.
Dario spent the weekend indexing all the photographs from the family trip to Japan.
index + [collection of items]
The librarian indexed the collection of old newspapers by date and by topic.
Sahil indexed every recipe in the notebook so his grandmother could find them easily.
The software program automatically indexes new files when you save them to the folder.
文法句型
index + noun (book, collection, data)
用法筆記
The object is the material being organised (a book, a database), not the list itself — you index a collection, not an index.
常見錯誤
2. to link wages, pensions, prices, or interest rates to a standard measure, so tha
to link wages, pensions, prices, or interest rates to a standard measure, so that they change automatically when that measure changes.
The government indexed the pension payments to match the rising cost of living.
passive: be indexed to [standard measure]
Many union contracts index annual wage increases to the rate of inflation.
Rania discovered that her rent was indexed to inflation and would increase next year.
The country indexed its interest rates to the foreign exchange rate to keep prices stable.
文法句型
be indexed to + noun
index + noun + to + noun
用法筆記
Almost always used in financial or economic contexts. The passive construction 'be indexed to' is the most common pattern.