progestin pro·ges·tin (prō-jěs'tĭn)
n.
A natural or synthetic progestational substance that mimics some or all of the actions of progesterone.
A crude hormone of the corpus luteum from which progesterone can be isolated in pure form. No longer in technical use.
progestogen pro·ges·to·gen (prō-jěs'tə-jən)
n.
Any of various substances having progestational effects; a progestin.