indoleacetic acid
noun
in·dole·ace·tic acid ˌin-(ˌ)dō-lə-ˈsē-tik- 
: a crystalline plant hormone C10H9NO2 that is a naturally occurring auxin promoting growth and rooting of plants
Word History
First Known Use
1937, in the meaning defined above
Medical Definition
indoleacetic acid
noun
in·dole·ace·tic acid ˈin-ˌdōl-ə-ˌsēt-ik-
: a crystalline compound C10H9NO2 that is formed from tryptophan in plants and animals, is present in small amounts in normal urine, and acts as a growth hormone in plants
called also heteroauxin