Is it ensure, insure, or assure?
c.1200, worn-down form of Old English alswa "quite so" (see also), fully established by c.1400. Equivalent to so; any distinction in use is purely idiomatic. Related to German als "as, than," from Middle High German also. 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! (i.e. "as if that really could happen") is attested from 1995, an exact duplication of Latin quasi.
Old English swylc, swilc from a Proto-Germanic compound *swalikaz "so formed" (cf. Old Saxon sulik, Old Norse slikr, Old Frisian selik, Middle Dutch selc, Dutch zulk, Old High German sulih, German solch, Gothic swaleiks), from swa "so" (see so) + *likan "form," source of Old English gelic "similar" (see like). Colloquial suchlike (early 15c.) is pleonastic.
The symbol for the element arsenic.
Latin auris sinistra (left ear)
The symbol for arsenic.