late 12c., worn-down form of O.E. alswa "quite so" (see also). Equivalent to so; any distinction in use is purely idiomatic. Related to Ger. als "as, than." Phrase as well "just as much" is recorded from late 15c.; the phrase also can imply "as well as not," "as well as anything else." Interjection of incredulity as if! is attested from 1995.