Penetrate
mid 16th century: from Latin penetrat- ‘placed or gone into’, from the verb penetrare ; related to penitus ‘inner’.
wiktionary
From Latin penētrātus, past participle of penētrō(“to put, set, or place within, enter, pierce, penetrate”), from penes(“within, with”) by analogy to intrō(“to go in, enter”).
etymonline
penetrate (v.)
1520s, "to pierce into or through," from Latin penetratus, past participle of penetrare "to put or get into, enter into; cause to go into." This is related to penitus "within, inmost, interior," penetralis "penetrating; innermost;" penus "innermost part of a temple, store of food," penarius "used for storing food;" Penates "household gods."
All are from penus/penoris "food, provisions," from Proto-Italic *penos, from PIE *penos "food" (source also of Lithuanian penėti "to feed"). De Vann writes that "The semantic appurtenance to 'feed' is explained by Stüber as 'what one feeds with' ('food') > 'the place one feeds at' > 'interior, home'."
The figurative senses of "enter and affect deeply, influence, impress" and "gain intellectual or spiritual access" are from 1580s. Related: Penetrated; penetrating.
