Irregular  —adj. 1 not regular; unsymmetrical, uneven; varying in form. 2 not occurring at regular intervals. 3 contrary to a rule, principle, or custom; abnormal. 4 (of troops) not belonging to the regular army. 5 (of a verb, noun, etc.) Not inflected according to the usual rules. 6 disorderly. —n. (in pl.) Irregular troops.  irregularity n. (pl. -ies). Irregularly adv.