word-forming element meaning "in; into," from French and Old French en-, from Latin in- "in, into" (from PIE root *en "in"). Typically assimilated before -p-, -b-, -m-, -l-, and -r-. Latin in- became en- in French, Spanish, Portuguese, but remained in- in Italian.
Also used with native and imported elements to form verbs from nouns and adjectives, with a sense "put in or on" (encircle), also "cause to be, make into" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as ensure/insure, and most en- words in English had at one time or another a variant in in-, and vice versa.
"strong thread made from twisted strands," Old English twin "double thread," from Proto-Germanic *twiznaz "double thread, twisted thread" (source also of Dutch twijn, Low German twern, German zwirn "twine, thread"), from PIE root *dwo- "two."
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<a href="https://www.etymonline.com/word/entwine">Etymology of entwine by etymonline</a>
Harper, D. (n.d.). Etymology of entwine. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/entwine