1 in-, il-, im-, ir-

[L. in, in, into; rel. to Gr. en, Eng. in ]
Prefix meaning in, inside, within, as in incorporated; also used as a transitive or intensive prefix, as in inflammable. In- remains in- before vowels and c, f, g, h, n, q, s, t, v; it becomes il- before l; im- before b, m, and p; and ir- before r.