The Collaborative International Dictionary of English v.0.48:
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]WordNet (r) 3.0 (2006):
indoleacetic acid n 1: a plant hormone promoting elongation of stems and roots [syn: indoleacetic acid, IAA]