function

/ˈfʌŋkʃn/ (bre, ipa) · /ˈfʌŋkʃn/ (ame, ipa) · /ˈfəŋ(k)-shən/ (ame, mw) · /ˈfʌŋk.ʃən/ (bre, ipa) · /ˈfʌŋk.ʃən/ (ame, ipa)

function — noun

  • functionsingular
  • functionsplural

1. the main job, use, or reason that something or someone exists within a system or

1.名詞B1
釋義

the main job, use, or reason that something or someone exists within a system or situation

例句

The main function of a refrigerator is to keep food cold and fresh.

function of — purpose/use pattern

Christopher's function in the team is to manage the project budget and timeline.

同義詞
  • purpose

    more common for the intended reason something exists; function focuses on the job it does in a system

  • role

    emphasizes expected contribution within a group, especially of a person

  • use

    more practical and concrete; tells you how to employ something

  • duty

    restricted to moral or professional obligations of a person

文法句型

function of [noun]

serve/perform/have a function

常見錯誤

❌The function of the meeting is for discussing the budget.
✅The purpose of the meeting is to discuss the budget.
💡For the reason behind an event or plan, 'purpose' or 'point' is more natural than 'function'.

2. a large, formal gathering of people for a ceremony, celebration, or official occ

2.名詞B2
釋義

a large, formal gathering of people for a ceremony, celebration, or official occasion

例句

The ambassador attended a formal function at the city museum last night.

formal function — formal social event

Élise wore a long gown to the charity function at the grand hotel.

同義詞
  • event

    more general; can be formal or informal, large or small

  • gathering

    softer, less formal tone; any group of people meeting

  • ceremony

    specifically religious or ritualistic; more solemn than a function

文法句型

[adjective] function

function at [venue]

用法筆記

Often paired with adjectives that describe the type of event, such as 'charity function', 'diplomatic function', or 'fundraising function'. Not used for small, informal gatherings with friends.

常見錯誤

❌I invited a few friends over for a small function at my flat.
✅I invited a few friends over for a small party at my flat.
💡'Function' is for formal, organised gatherings, not casual get-togethers.

3. the way a machine, system, or living body behaves and carries out its tasks

3.名詞B2
釋義

the way a machine, system, or living body behaves and carries out its tasks

例句

The brain's function depends on a steady supply of oxygen and nutrients.

body/organ + function — physiological operation

Hiro noticed that the function of the old engine had become less smooth.

同義詞
  • operation

    more technical; used especially for machines and formal systems

  • performance

    focuses on how well something works, not simply that it works

  • working

    more informal; common in everyday speech about devices

文法句型

[noun] function

function of [organ/system/machine]

用法筆記

Frequently used with body parts or physiological systems (liver function, brain function, immune function) and machines (engine function, system function). Often modified by adjectives describing quality, such as 'normal function', 'proper function', or 'impaired function'.

常見錯誤

❌I checked the function of my phone by looking at its colour.
✅I checked whether my phone was functioning by making a call.
💡This sense describes how something operates, not its external features or condition.

4. a named block of code in a computer program that performs a specific task when a

4.名詞B2
釋義

a named block of code in a computer program that performs a specific task when activated

例句

The search function lets you find any file on your computer by name.

search/sort + function — software feature

Kofi wrote a function in Python that calculates the average temperature.

同義詞
  • routine

    older term; less common in modern programming than 'function'

  • method

    used in object-oriented programming; a function that belongs to a class

  • procedure

    similar to function but does not return a value

文法句型

call/define/use a function

[noun] function

用法筆記

In programming, a function is a reusable block of code. Common verb collocations include 'call a function', 'define a function', and 'write a function'. In everyday software use (apps, websites), 'function' can also refer to a feature or tool (e.g. 'search function', 'sort function').

常見錯誤

❌I need to replace a function in my computer's hardware.
✅I need to fix the login function in my program's code.
💡In computing, 'function' refers to software code, not physical hardware parts.

5. a relationship where one thing directly depends on or varies with another

5.名詞C1
釋義

a relationship where one thing directly depends on or varies with another

例句

In economics, supply is a function of demand and production costs.

X is a function of Y — dependency pattern

The quality of a crop is a function of rainfall and soil conditions.

同義詞
  • dependence

    noun form that directly states the relying relationship

  • correlation

    weaker than function; implies two things change together without one causing the other

文法句型

X is a function of Y

用法筆記

Typically appears in the pattern 'X is a function of Y', meaning X depends on Y or is determined by Y. Common in academic, economic, and technical writing. This sense does NOT refer to a specific job or purpose (noun 1).

常見錯誤

❌His happiness is a function of his new car.
✅His happiness depends on many factors, not just his new car.
💡'Is a function of' suggests a direct, measurable dependency. For personal emotions, 'depends on' is more natural.

6. a rule in mathematics that connects each input value to exactly one output value

6.名詞B2
釋義

a rule in mathematics that connects each input value to exactly one output value

例句

In the equation y = 2x + 1, y is a function of x.

function of x — mathematical relationship

The maths teacher asked the class to graph the function f of x equals x squared.

同義詞
  • mapping

    more informal term that describes how inputs are paired with outputs

  • relation

    broader category; every function is a relation, but not every relation is a function

文法句型

function of [variable]

function f(x)

[adjective] function

用法筆記

Distinguish from the computing sense (noun 4): in mathematics, a function is an abstract relationship between numbers, not a block of computer code. Common phrases include 'function of x', 'linear function', 'quadratic function', 'inverse function', and 'graph a function'.

常見錯誤

❌A function always goes up on the graph.
✅A function can go up, down, or stay flat
💡it only needs to give one output for each input.' — The defining feature of a mathematical function is the one-output-per-input rule, not the shape of its graph.

function — verb