irregular

irregular - noun

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

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

irregular - adjective

contrary to rule or accepted order or general practice
(used of the military) not belonging to or engaged in by regular army forces
(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
not occurring at expected times
falling below the manufacturer's standard
deviating from normal expectations; somewhat odd, strange, or abnormal
lacking continuity or regularity
(of a surface or shape); not level or flat or symmetrical
independent in behavior or thought

irregular - thesaurus