IAA n 1: a plant hormone promoting elongation of stems and roots [syn: {indoleacetic acid}, {IAA}] 2: Yemen-based terrorist group that supports al-Qaeda's goals; seeks to overthrow the Yemeni government and eliminate United States interests; responsible for bombings and kidnappings and killing western tourists in Yemen [syn: {Islamic Army of Aden}, {IAA}, {Islamic Army of Aden-Abyan}, {Aden-Abyan Islamic Army}]
IAA \IAA\ n. Indoleacetic acid, a plant hormone promoting elongation of stems and roots. [Acronym] Syn: indoleacetic acid. [WordNet 1.5]
indoleacetic acid \in"dole*a*cet"ic ac"id\ ([i^]n"d[=o]l), n. (Chem., Bot.) A plant hormone ({C10H9NO2}) recognized as the principle growth regulator in higher plants; called also {heteroauxin}. Abbreviated {IAA}. Chemically it is 1H-indole-3-acetic acid. [PJC]