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 only to describe foods with a sour taste. (Acerb is still around today, but now it's simply a less common synonym of acerbic.) Acerbic and acerb ultimately come from the Latin adjective acerbus, which can mean "harsh" or "unpleasant." Another English word that comes from acerbus is exacerbate, which means "to make more violent or severe."