acid

Universal Words noun, adjective noun 1 [U,C] (chemistry) a chemical compound, usually a liquid, that contains HYDROGEN and has a PH of less than seven. The HYDROGEN can be replaced by a metal to form a SALT. Acids are usually sour and can often burn holes in or damage things they touch. compareALKALI seealsoACETICACID, AMINOACID, CITRICACID, HYDROCHLORICACID, LACTICACID, NITRICACID, NUCLEICACID, SULPHURICACID 2 [U] (slang) = LSD adjective 1 (technical) that contains acid or has the essential characteristics of an acid; that has a PH of less than seven: Rye is tolerant of poor, acid soils. compareALKALINE 2 that has a bitter sharp taste SYNSOUR: acid fruit 3 (written) (of a person's remarks) critical and unkind SYNSARCASTIC: an acid wit