Affixes

This prefix is added to adjectives to give a negative sense (infertile, inarticulate, inexpensive, invariable) and to nouns to indicate a lack of something (inattention, incapacity, insensitivity). Many examples exist, but in‑ is not a living form, new words instead being created using un‑, to which it is closely related in sense. There is no clear rule deciding which should be used: see un‑ for more information. See also the next entry.

The prefix is spelled il‑ before stems beginning in l (illegitimate, illiberal), im‑ before b, m, and p (imbalance, immoral, impossible), and ir‑ before r (irrational, irregular).