while

while — conjunction

1. used to show that two events occur together during a shared period, without one

1.conjunctionA1
Definition

used to show that two events occur together during a shared period, without one preceding or interrupting the other.

Example

Bao listened to music while he cooked dinner for his family.

while + clause expressing simultaneous actions

The children played outside while their mother prepared lunch in the kitchen.

Common collocations
  • while + present participle
  • while + subject + verb
  • while + clause
Synonyms
  • when

    more general for time; 'when' does not emphasise simultaneity as strongly as 'while'

  • as

    more formal and often used for two developing actions happening together

  • during

    preposition, not conjunction; followed by a noun, not a clause

Grammar Patterns

while + clause (subject + verb)

while + present participle

Usage Note

A when-clause can sometimes replace while-clauses, but while emphasises the duration or simultaneity more clearly. When the subject of both clauses is the same, the participle form is common: 'She listened while cooking.'

Common Mistakes

I read a book while the rain.
I read a book while it was raining.
while must be followed by a clause (subject + verb), not a noun.
While he is tall, but his brother is short.
He is tall, while his brother is short.
do not add 'but' after while when contrasting.

2. used to introduce a fact that makes the main point seem surprising; although.

2.conjunctionB1
Definition

used to introduce a fact that makes the main point seem surprising; although.

Example

While the apartment is small, it feels surprisingly warm and comfortable.

while + clause at sentence start for concessive meaning

While Cole agrees with the overall goal, he strongly disagrees with the method proposed.

Common collocations
  • while + clause with contrasting information
Synonyms
  • although

    more common in speech; interchangeable with while in this sense

  • even though

    stronger emphasis on the surprising contrast

  • though

    more informal; can appear at the end of a sentence

Grammar Patterns

while + clause (stating a contrast with the main clause)

Usage Note

This sense of while is more common in formal or written English. In everyday conversation, although or even though are more frequent. The clause with while usually comes first, but it can appear in the middle for a milder contrast.

Common Mistakes

While the weather was bad, but we still went hiking.
While the weather was bad, we still went hiking.
do not add 'but' after while in concessive use; while already expresses the contrast.
While he is tired.' (as a complete sentence)
While he is tired, he keeps working.
a concessive while-clause needs a main clause to complete the meaning.

3. used to compare two facts or situations and show that they are different in a no

3.conjunctionB2
Definition

used to compare two facts or situations and show that they are different in a noticeable way.

Example

Tara prefers green tea, while her brother drinks black coffee every morning.

while contrasting two people's preferences

In Japan people drive on the left, while in the US they drive on the right.

Common collocations
  • while + clause presenting a contrasting fact
Synonyms
  • whereas

    fully interchangeable; whereas is more formal

  • but

    simpler and more common in speech; less precise for balanced comparison

  • in contrast

    more formal; often starts a new sentence

Grammar Patterns

clause A + while + clause B (contrasting)

Usage Note

Unlike the concessive sense (Sense 2), this sense does not express contradiction — it simply draws a balanced comparison. Whereas is a direct synonym here, while also works in this sense because the contrast is not surprising.

Common Mistakes

I like swimming, while I also like running.
I like swimming, while my brother prefers running.
while in this sense requires genuine contrast, not addition.
While he is tall, his brother is short, while they are both friendly.
He is tall, while his brother is short.
avoid using while twice in the same sentence for different types of contrast.
Idioms

while you’re/I’m etc. at it

idiom

Used to suggest doing an extra task during another activity.

Sara is making tea, so she can bring me a cup while she's at it.

If you're going to the store, could you buy milk while you're at it?

while — noun

while — preposition

while — verb

Word family

Synonym discussion

Sense: conjunction/1

While, when, as, during, and meanwhile all relate to time, but they are used differently. While emphasises that two actions happen at the same time and often for a similar duration — for example, 'Bao listened to music while he cooked.' When is more general and can refer to a single point in time: 'Bao listened to music when he entered the kitchen.' As is used for two actions that develop together: 'The music got louder as he stirred the pot.' During is a preposition, not a conjunction, so it must be followed by a noun: 'during dinner', not 'during he cooked.' Meanwhile is an adverb that starts a new sentence: 'Bao cooked dinner. Meanwhile, the children played in the garden.' For learners, the key rule is: use while when the two actions overlap over a period; use when for a single moment or sequence.

when ↗as ↗during ↗meanwhile ↗

Common collocations

Nouns

  • a while
  • quite a while
  • a long while
  • a short while

Phrases

Prepositions

  • for a while
  • after a while
  • in a while

Etymology

Old EnglishMiddle EnglishModern English

While comes from Old English hwīl, meaning 'a space of time' or 'a period of rest'. This noun sense is over a thousand years old. By the early Middle English period, hwīl was already being used as a conjunction to mean 'during the time that'. The verb phrase 'while away' (to pass time pleasantly) appears in the 1600s, originally meaning to cause time to pass — the 'away' part emphasises the idea of making time disappear agreeably. The concessive and contrastive conjunction senses ('although' and 'whereas') developed naturally from the temporal sense, as two events happening at the same time were easily extended to two ideas being compared.