as

(adverb): To such an extent or degree; to the same extent or degree.
(adverb): Considered to be, in relation to something else; in the relation (specified).
(adverb): For example; for instance. (Compare such as.)
(preposition): Introducing a basis of comparison, with an object in the objective case.
(preposition): In the role of.
(conjunction): In the (same) way or manner that; to the (same) degree that.
(conjunction): At the time that; during the time when:
(conjunction): Being that, considering that, because, since.
(conjunction): Introducing a comparison with a hypothetical state (+ subjunctive, or with the verb elided): as though, as if.
(conjunction): Functioning as a relative conjunction, and sometimes like a relative pronoun: that, which, who. (See usage notes.)
(conjunction): (possibly obsolete) Than.