Irregular

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

merchandise that has imperfections

contrary to rule or accepted order or general practice

not occurring at a regular rate or fixed intervals

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

(of solids) not having clear dimensions that can be measured

failing to meet a standard of manufacture due to an imperfection

deviating from normal expectations

lacking continuity or regularity

(of a surface or shape)

independent in behavior or thought