ETYM Pref. ir- not + regular: cf. French irrégulier.
1. Contrary to rule or accepted order or general practice.
2. Independent in behavior or thought; SYN. maverick, unorthodox.
3. Lacking continuity or regularity; SYN. temporary.
4. Not occurring at expected times; SYN. unpredictable.
5. Said of a surface: not level or flat.
6. Used of the military: not belonging to or engaged in by regular army forces.