Entries linking to interpenetration
A living prefix in English from 15c. and used with Germanic as well as Latinate words. Spelled entre- in French; most words borrowed into English in that form were re-spelled 16c. to conform with Latin except entertain, enterprise. In Latin, spelling shifted to intel- before -l-, hence intelligence, etc.
early 15c., penetracioun, "a puncture, a penetrating wound," from Latin penetrationem (nominative penetratio) "a penetrating or piercing," noun of action from past-participle stem of penetrare "to put or get into, enter into" (see penetrate). From c. 1600 as "insight, discernment, shrewdness;" the sexual sense is attested from 1610s; meaning "act of penetrating or piercing" is from 1620s; in optics, by 1799.