adverb(usually as —— as)
Middle English: reduced form of Old English alswā 'similarly'(see also)
1 A small, seemingly innocent word, as is so frequently misused (or not used where needed) that interested writers are advised to consult a full-length usage guide for counsel on its proper use. As is often used in causal senses in place of because or since (As Julie wasn’t hungry, she ordered only a cup of coffee); in such constructions, where as may cause confusion, it is generally advisable to use the unambiguous because, or since. 2 On whether it is more correct to say he’s not as shy as I rather than he’s not as shy as me, or I live in the same street as she rather than I live in the same street as her, see personal pronoun (usage). 3 For a discussion of when to use as rather than like, see like1 (usage).
A word that can be used in three main ways:Subordinating conjunctionIt can introduce a number of different types of adverbial clause: TimeAs the train drew into Grand Central, Louie nudged his sleeping sister. ReasonAs these are fast-drying, the application technique is slightly different. MannerThe talk that night was about experiments carried out to explain why people behaved as they did. CommentThat, as I understand it, is the law. The most common of these four uses are the first two; in them as can mean ‘while’ or ‘because’. Occasionally this can cause confusion if a sentence is carelessly constructed. For example:I left the farm as it was getting late. Does this mean whenit was getting late, or becauseit was getting late?PrepositionShould I get a job as a bartender? AdverbIt can also be used as an adverb in comparisons:He’s as happy as a kid in a candy store.