English speakers created "acerbic" in the 19th century by adding "-ic" to the adjective "acerb." "Acerb" had been around since the 17th century, but for most of that time it had been used with only a literal "sour-tasting" sense. (The word acerb is still around today, but it is now simply a less common synonym of "acerbic.") "Acerbic" and "acerb" ultimately come from the Latin adjective acerbus, which can mean "harsh," "bitter," or "unpleasant." Another English word that comes from "acerbus" is "exacerbate," which means "to make more violent, bitter, or severe."