Word Origin & History
en-prefix meaning "cause to be, make" (endear); "put in or on" (encircle); from O.Fr. en-, from L. in- "in, into." Also used as an intensive (enclose). Spelling variants in O.Fr. brought over into M.E. account for parallels such as assure/insure/ensure. Many words beginning with en- in Mod.Eng. are transparent
(enforce, etc.) and etymologies can be found in listings for their stems. Words listed here include those whose unprefixed form is not an obvious word in Eng. (encroach) or whose meaning has drifted significantly (engrain).
-ensuffix forming verbs (e.g. darken, weaken), from adjectives or from nouns, from O.E. -nian, from P.Gmc. *-inojan. Mostly active in M.E.
-ensuffix added to nouns to produce adjectives meaning made of, of the nature of (e.g. golden, oaken), corresponding to L. -ine. Common in O.E. and M.E., surviving words with it now are largely discarded in everyday use and the simple form of the noun serves as an adjective as well.