Origin of in-1
- a prefix of Latin origin meaning primarily “in,” but used also as a verb-formative with the same force as in-1 (incarcerate; incantation).
Origin of in-2
- a prefix of Latin origin, corresponding to English un-, having a negative or privative force, freely used as an English formative, especially of adjectives and their derivatives and of nouns (inattention; indefensible; inexpensive; inorganic; invariable). It assumes the same phonetic phases as in-2 (impartial; immeasurable; illiterate; irregular, etc.). In French, it became en- and thus occurs unfelt in such words as enemy (French ennemi, Latin inimicus, lit., not friendly).
Origin of in-3
il-, im- or ir-
- not; non-incredible; insincere; illegal; imperfect; irregular Compare un- 1
il-, im- or ir-
- in; into; towards; within; oninfiltrate; immigrate
- having an intensive or causative functioninflame; imperil
Word Origin and History for in-
prefix meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant), from Latin in- "not," cognate with Greek an-, Old English un-, from PIE *ne "not" (see un- (1)).
element meaning "into, in, on, upon" (also im-, il-, ir- by assimilation of -n- with following consonant), from Latin in- "in" (see in). In Old French this often became en-, which usually was respelled in English to conform with Latin, but not always, which accounts for pairs like enquire/inquire. There was a native form, which in West Saxon usually appeared as on- (cf. Old English onliehtan "to enlighten"), and some verbs survived into Middle English (cf. inwrite "to inscribe"), but all now seem to be extinct. Not related to in- (1) "not," which also was a common prefix in Latin: to the Romans impressus could mean "pressed" or "unpressed."