Irregular

independent in behavior or thought

not occurring at a regular rate or fixed intervals

deviating from normal expectations; somewhat odd, strange, or abnormal

lacking continuity or regularity

contrary to rule or accepted order or general practice

(used of the military) not belonging to or engaged in by regular army forces

failing to meet a standard of manufacture due to an imperfection

(of a surface or shape); not level or flat or symmetrical

merchandise that has imperfections; usually sold at a reduced price without the brand name

a member of an irregular armed force that fights a stronger force by sabotage and harassment

(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement