A pregnene is an alkene derivative of a pregnane. An example is cortisone. ...
An unsaturated steroid of primarily terminological importance; utilised in systematic nomenclature of appropriate 21-carbon steroids. ... (05 Mar 2000) ... 
Type: Term Pronunciation: preg′nēn Definitions: 1. An unsaturated steroid of primarily terminologic importance; utilized in systematic nomenclature of appropriate 21-carbon steroids.