(1) Not occurring at expected times
(2) Independent in behavior or thought
"She led a somewhat irregular private life"
(3) Of a surface; not level or flat
"Walking was difficult on the irregular cobblestoned surface"
(4) Lacking continuity or regularity
"An irregular worker"
"Employed on a temporary basis"
(5) Deviating from normal expectations; somewhat odd, strange, or abnormal
"These days large families are atypical"
"Atypical clinical findings"
"Highly irregular behavior"
(6) Contrary to rule or accepted order or general practice
"Irregular hiring practices"
(7) (of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
(8) (used of the military) not belonging to or engaged in by regular army forces
(9) Merchandise that has imperfections; usually sold at a reduced price without the brand name
(10) A member of an irregular armed force that fights a stronger force by sabotage and harassment