c.1200, from Old English þeah, and in part from Old Norse þo "though," both from Proto-Germanic *thaukh (cf. Gothic þauh, Old Frisian thach, Middle Dutch, Dutch doch, Old High German doh, German doch), from PIE demonstrative pronoun *to- (see that). The evolution of the terminal sound did not follow laugh, tough, etc., though a tendency to end the word in "f" existed c.1300-1750 and persists in dialects.
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.
The symbol for the element arsenic.
Latin auris sinistra (left ear)
The symbol for arsenic.