- in- (1)
- prefix meaning "not, opposite of, without" (also im-/il-/ir- by assimilation of -n- with following consonant), from L. in- "not," cognate with Gk. an-, O.E. un- (see un- (1)).
- in- (2)
- prefix meaning "into, in, on, upon" (also im-; il-; ir- by assimilation of -n- with following consonant), from L. in- "in" (see in). In O.Fr. this often became en-, which was usually respelled in Eng. to conform with L., but not always, which accounts for pairs like enquire/inquire. There was a native form, which in W.Saxon usually appeared as on- (cf. O.E. onliehtan "to enlighten"), and some verbs survived into M.E. (cf. inwrite "to inscribe"), but all now seem to be extinct.