English

interpenetrate

From inter- + penetrate.

Proto-Indo-European *h₁én ‘in’

Proto-Indo-European *h₁entér ‘between’

Proto-Italic *n̥ter ‘between’

Latin inter ‘between’

Proto-Indo-European *pen-

Latin penētrō ‘to put, set, or place within, enter, pierce,…’

Latin penētrātus

Today it means

verb To penetrate mutually or reciprocally.

Language periods are conventional ranges, not dates for this word.

Etymograph / interpenetrate