(with an and plural) An instance of this; a breach of rule or principle; an irregular, lawless, or disorderly act.

As a count noun: an odd thing or characteristic; an oddity; a peculiarity; †an irregularity, a discrepancy (obsolete).

An irregular bend; a crook, a kink; also, a confused intertwining, as of a yarn or thread; a tangle. Chiefly figurative.

A deviation from an otherwise regular process, pattern, etc.; an irregularity; an anomaly; a peculiar or unexpected feature of something.