n. In botany, a genus of tall herbaceous plants of southern Europe and Africa, natural order Acanthaceæ.n. [lowercase] The common name of plants of this genus. In zoology, a genus of crustaceans. [lowercase] In architecture, a characteristic ornament derived from or resembling the conventionalized foliage or leaves of the acanthus, used in capitals of the Corinthian and Composite orders, and in Roman, Byzantine, medieval, and Renaissance architecture generally, as upon friezes, cornices, modillions, etc.