1,3,5(10)-Estratriene;the hypothetical triply-unsaturated estrane that is the nucleus of most naturally occurring oestrogenic steroids in animals. ... (05 Mar 2000) ... 
Type: Term Pronunciation: es′tră-trī′ēn Definitions: 1. The hypothetic triply unsaturated estrane that is the nucleus of most naturally occurring estrogenic steroids in animals.