English Reference

Word

who

US/ˈhu/

UK/hˈuː/

Definitions

01asking for identity

A1 · Beginner

pron. you use this to ask which person or people did something.

pron. an interrogative pronoun used to request the identity of a person or group of people.

“Who is that man standing by the door?”

“Who was responsible for authorizing the expenditure without consulting the board of directors first?”

Usage

Used as the subject of a sentence or question.

Pitfall

Who did you see at the party?

Whom did you see at the party?

In very formal English, 'who' is for the subject and 'whom' is for the object, though 'who' is now common for both in speech.

Teaching tip

While 'whom' is technically correct for objects, 'who' is the standard choice for almost all modern spoken contexts.

Synonyms

which person

02adding information

A1 · Beginner

pron. you use this to give more details about a person you just mentioned.

pron. a relative pronoun used to introduce a clause that provides more information about a human antecedent.

“The woman who lives next door is a famous doctor.”

“The candidates who successfully complete the first round of interviews will be invited back for a technical assessment.”

Usage

Introduces a relative clause.

Pitfall

The car who I bought is red.

The car that I bought is red.

Use 'who' only for people; use 'which' or 'that' for objects.

Teaching tip

Remind students that 'who' is for people and 'which' is for things, though 'that' can sometimes be used for both.

Synonyms

03the identity of a person

B2 · Upper Intermediate Uncountable noun Informal

n. the identity of a person, often used when the person is unknown.

n. the identity or specific person involved in a situation, often used in phrases concerning mystery or investigation.

“The police are still trying to find out the who and the why of the crime.”

“The mystery isn't just about the how, but the who—identifying the person behind the anonymous letters.”

Usage

Often used in the phrase 'the who, what, where, and why'.

Teaching tip

This noun use is idiomatic and usually appears alongside other question words treated as nouns.

Synonyms

Confusables

who vs whom

Who functions as the subject of a verb, while whom functions as the object of a verb or preposition.

RememberWho = He. Whom = Him.

Idioms

Grammar

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.A1 MoversIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.2.0–3.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 1.0–1.50–23TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.120–224
Frequency
Very common
Level
A1 · BeginnerOxford
Updated

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English Reference