a prefix occurring originally in loanwords from French and productive in English on this model, forming verbs with the general sense “to cause (a person or thing) to be in” the place, condition, or state named by the stem; more specifically, “to confine in or place on” (enshrine; enthrone; entomb); “to cause to be in” (enslave; entrust; enrich; encourage; endear); “to restrict” in the manner named by the stem, typically with the additional sense “on all sides, completely” (enwind; encircle; enclose; entwine). This prefix is also attached to verbs in order to make them transitive, or to give them a transitive marker if they are already transitive (enkindle; enliven; enshield; enface).
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).