(1):
(a.) Deviating from ordinary forms or rules; irregular; anomalous; abnormal.
(2):
(n.) A word which is irregular or anomalous either in declension or conjugation, or which deviates from ordinary forms of inflection in words of a like kind; especially, a noun which is irregular in declension.
(3):
(n.) Any thing or person deviating from the common rule, or from common forms.