indoleacetic acid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A plant hormone, C₁₀H₉NO₂, that stimulates growth.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry an auxin plant hormone, synthesized in leaves, that stimulates growth, especially in the presence of ethylene

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a plant hormone promoting elongation of stems and roots