1. in- a prefix representing Englishin (income; indwelling; inland), used also as a verb-formative with transitive, intensive, or sometimes little apparent force (intrust; ingulf).
2. in- a prefix of Latinoriginmeaning primarily “in,” but used also as a verb-formative with the sameforce as in-1 (incarcerate; incantation).
3. in- a prefix of Latin origin, corresponding to Englishun-, having a negative or privative force, freely used as an English formative, esp. of adjectives and their derivatives and of nouns (indefensible; inexpensive; invariable). It has the same variants before consonants as in-2 (immeasurable; illiterate; irregular, etc.).
1. (prefix)in- used with some adjectives and nouns to form a word with the oppositemeaning Inappropriate is the opposite of appropriate.
Definition of 'in-'
Webster Dictionary
1. in- a prefix from Eng. prep. in, also from Lat. prep. in, meaning in, into, on, among; as, inbred, inborn, inroad; incline, inject, intrude. In words from the Latin, in- regularly becomes il- before l, ir- before r, and im- before a labial; as, illusion, irruption, imblue, immigrate, impart. In- is sometimes used with an simpleintensiveforce
2. in- an inseparable prefix, or particle, meaning not, non-, un- as, inactive, incapable, inapt. In- regularly becomes il- before l, ir- before r, and im- before a labial
Definitions of in- 
