Acrostic \A*cros"tic\, n. [Gr. ?; ? extreme + ? order, line, verse.] 1. A composition, usually in verse, in which the first or the last letters of the lines, or certain other letters, taken in order, form a name, word, phrase, or motto. 2. A Hebrew poem in which the lines or stanzas begin with the letters of the alphabet in regular order (as Psalm cxix.). See {Abecedarian}. {Double acrostic}, a species of enigma