WordWeb Online

1. Any undertaking that is easy to do
   "marketing this product will be no child's play";
   - cinch [informal], breeze [informal], picnic [informal], snap [informal], duck soup [N. Amer, informal], pushover, walkover, piece of cake [informal], doss [Brit, informal]
    
2. Activity by children that is guided more by imagination than by fixed rules
   "Freud believed in the utility of child's play to a small child";
   - play

Type of: diversion, labor [US], labour [Brit, Cdn], project, recreation, task, undertaking