[ac.id] adj [F or L; F acide, fr. L acidus, fr. acere to be sour--more at acet-] (1626) 1 a: sour, sharp, or biting to the taste b: sharp, biting, or sour in manner, disposition, or nature "an ~ individual" c: sharply clear, discerning, or pointed "an ~ wit" d: piercingly intense and often jarring "~ yellow"
2. a: of, relating to, or being an acid; also: having the reactions or characteristics of an acid "~ soil" "an ~ solution" b of salts and esters: derived by partial exchange of replaceable hydrogen c: containing or involving the use of an acid (as in manufacture) d: marked by or resulting from an abnormally high concentration of acid "~ indigestion"
3: relating to or made by a process (as in making steel) in which the furnace is lined with acidic material and an acidic slag is used
4: rich in silica "~ rocks" -- ac.id.ly adv -- ac.id.ness n
acid n (1696) 1: a sour substance; specif: any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, redden litmus, and have a pH less than 7, that are hydrogen-containing molecules or ions able to give up a proton to a base, or that are substances able to accept an unshared pair of electrons from a base
2: something incisive, biting, or sarcastic "a social satire dripping with ~"
3: lsd -- ac.idy adj