when
A1All registers: formal, informal, spoken, written.
Definition
Meaning
Used to ask or refer to the time at which something happens or is expected to happen.
Also used to introduce a clause referring to the time of an event, or to introduce a relative clause specifying the point in time something occurs. Can function as an interrogative adverb, relative adverb, and subordinating conjunction.
Linguistics
Semantic Notes
"When" can express simultaneity (at the same time that), immediacy (as soon as), or a general time condition. As a relative adverb, it can refer to a time previously mentioned. In informal questions, it can imply surprise or criticism (e.g., "When did you last clean this?").
Dialectal Variation
British vs American Usage
Differences
Minimal syntactic differences. In informal UK English, "when" is sometimes used in tag questions with "isn't it?" (e.g., "It was Friday when he arrived, wasn't it?"). In US English, this is less common.
Connotations
Both varieties use "when" identically for core functions.
Frequency
Equally frequent in both dialects.
Vocabulary
Collocations
Grammar
Valency Patterns
When + clause (main verb)Preposition + noun phrase + when + clauseBe + when + clause (defining time)Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “Say when (while pouring a drink)”
- “When in Rome (do as the Romans do)”
- “When hell freezes over”
- “When pigs fly”
Usage
Context Usage
Business
Used in scheduling, project timelines, and deadlines (e.g., 'Let me know when the report is ready.').
Academic
Used to establish temporal relationships in historical or scientific processes (e.g., 'The experiment failed when the temperature exceeded the threshold.').
Everyday
Ubiquitous for making plans and asking about time (e.g., 'When are you coming over?').
Technical
Used in programming and logic to define conditional events (e.g., 'Execute the function when the button is clicked.').
Examples
By Part of Speech
adverb
British English
- When did the post arrive?
- I recall the summer when we first met.
American English
- When is your appointment?
- That was the year when everything changed.
Examples
By CEFR Level
- When is your birthday?
- I eat breakfast when I get up.
- When does the shop close?
- Call me when you have the results.
- There was a time when I enjoyed running.
- Do you know when the last train leaves?
- He was midway through his speech when the fire alarm sounded.
- The period when inflation was highest followed the oil crisis.
- She'll decide when she's seen all the options.
- When viewed from a historical perspective, the decision seems misguided.
- The precise moment when the tectonic plates shifted was recorded by sensors.
- He demonstrated remarkable composure when confronted with the allegations.
Learning
Memory Aids
Mnemonic
WHEN asks about TIME. Both WHEN and TIME contain the letter 'E'.
Conceptual Metaphor
TIME IS A LOCATION (e.g., 'When we get to the weekend...').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid using "when" to translate "когда" in indirect questions where "if/whether" is correct (e.g., 'I don't know if/whether he is coming' NOT 'I don't know when he is coming').
- Do not confuse "when" (время) with "if" (условие).
Common Mistakes
- Using future tense after 'when' in subordinate clauses (e.g., 'I'll call you when I will arrive' should be 'I'll call you when I arrive').
- Overusing commas before 'when' in defining relative clauses (e.g., 'The day when we met was sunny' usually needs no comma).
Practice
Quiz
Which sentence uses 'when' CORRECTLY?
FAQ
Frequently Asked Questions
No, in subordinate clauses introduced by 'when' (referring to future time), use the present simple tense, not the future tense (e.g., 'I will call you when I arrive,' not 'when I will arrive').
'When' typically refers to a point in time or a single event. 'While' refers to a period of time or simultaneous ongoing actions (e.g., 'The phone rang when I was leaving' vs. 'The phone rang while I was cooking').
Primarily, no. 'When' is a temporal word. For conditional meanings, use 'if' (e.g., 'If you are tired, go to bed' not 'When you are tired, go to bed' unless you mean every time you are tired).
Use a comma before 'when' if it introduces extra, non-essential information (a non-restrictive clause). Do not use a comma if the 'when' clause is essential to defining the noun (a restrictive clause). Compare: 'Summer, when it's hot, is my favourite season.' (extra info) vs. 'The day when we met was Tuesday.' (defining).
Collections
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Common Questions
A1 · 31 words · Question words and phrases for basic communication.