indoleacetic acid /(ĭn"dōl)/

in·dole·a·cet·ic ac·id

indoleacetic acid

n.
  1. 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. (Chem., Bot.)