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.
word-forming element meaning "make, make into," from French -fier, from Latin -ficare, combining form of facere "to make" (from PIE root *dhe- "to set, put").
word-forming element meaning "long, abnormally large, on a large scale," taken into English via French and Medieval Latin from Greek makros "long, large," from PIE root *mak- "long, thin."
word-forming element meaning "against, in opposition," from Latin adverb and preposition contra "against" (see contra (prep., adv.)). The Latin word was used as a prefix in Late Latin. In French, it became contre- and passed into English as counter-. The Old English equivalent was wiðer (surviving in withers and widdershins), from wið "with, against."