en-

{{11}}en- (1) assimilated to -p-, -b-, -m-, -l-, -r-, prefix meaning "in, into," from French, O.Fr. en-, from L. in- "in, into" (see IN- (Cf. in-) (2)). Also used with native elements to form verbs from nouns and adjectives, "put in or on" (encircle), also "cause to be, make" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as ASSURE (Cf. assure)/ENSURE (Cf. ensure)/INSURE (Cf. insure).

{{12}}en- (2) assimilated to -p-, -b-, -m-. -l-, -r-, "near, at in, on, within," from Gk. en "in," cognate with L. in (see IN (Cf. in)), and with EN- (Cf. en-) (1).