irregular in WordNet English dictionary

1. deviating from normal expectations; somewhat odd, strange, or abnormal
   "these days large families are atypical"; "atypical clinical findings"; "atypical pneumonia"; "highly irregular behavior"
   atypical  irregular 
   
2. contrary to rule or accepted order or general practice
   "irregular hiring practices"
   irregular 
   
3. (of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
   irregular 
   
4. (used of the military) not belonging to or engaged in by regular army forces
   "irregular troops"; "irregular warfare"
   irregular 
   
5. falling below the manufacturer's standard
   "irregular jeans"
   irregular 
   
6. lacking continuity or regularity
   "an irregular worker"; "employed on a temporary basis"
   irregular  temporary 
   
7. not occurring at expected times
   irregular  unpredictable 
   
8. independent in behavior or thought
   "she led a somewhat irregular private life"; "maverick politicians"
   irregular  maverick  unorthodox 
   
9. (of a surface or shape); not level or flat or symmetrical
   "walking was difficult on the irregular cobblestoned surface"
   irregular 
   

1. a member of an irregular armed force that fights a stronger force by sabotage and harassment
   guerrilla  guerilla  irregular  insurgent 
   
2. merchandise that has imperfections; usually sold at a reduced price without the brand name
   irregular  second