irregular /ɪˈregjələr/ adjective
TIME › Irregular actions or events happen with a different amount of time between each one: an irregular heartbeat They met at irregular intervals.
SHAPE › not smooth or straight, or having parts that are different sizes: an irregular coastline
GRAMMAR › not following the general rules in grammar: irregular verbs/plurals
BEHAVIOUR UK formal › slightly illegal, or not done in the usual and acceptable way: He led a very irregular life. irregularity /ɪˌregjəˈlærəti/ noun [C, U] irregularly adverb