While

While is a word in the English language that functions both as a noun and as a subordinating conjunction. Its meaning varies largely based on its intended function, position in the phrase and even the writer or speaker's regional dialect. As a conjunction, it is synonymous with the word whilst, a form often considered archaic in American English, as well as in some style guides on both sides of the Atlantic.

Usage

Noun

A while and awhile are often confused due to the fact that while is often accompanied by the indefinite article. The main difference is that a while means "an amount of time" or "some duration" whereas awhile is an adverb meaning "for some amount of time" or "for some duration".

"I slept for a while before dinner."

"I slept awhile before dinner."

Both of these sentences yield the same effective meaning. Whilst is only a conjunction, and so its use here would be incorrect.

Conjunction

The primary function of the word as a conjunction is to indicate that two separate clauses occur at the same time.

"The days were hot while we were on vacation."

"I read a magazine while I was waiting."

While can also be legitimately used in the contrastive sense, comparable to the words "although" or "whereas", provided that it is not ambiguous (although some commentators, such as Eric Partridge, have disapproved of such use):

"While I like cats, my husband is allergic."

"While Sally plays, Sue works."

The latter sentence can mean either "during the time that Sally plays, Sue works" or "although Sally plays, Sue works" and is thus ambiguous.

Fowler's Modern English Usage disapproves of several uses of the conjunctive while.