onside Syllabification: (on·side)Pronunciation: /ˈänˈsīd, ˈôn-/Translate onside | into French | into Italian Definition of onside adjective & adverb (of a player, especially in soccer or hockey) occupying a position on the field where playing the ball or puck is allowed; not offside. onside in other Oxford dictionaries Definition of onside in the British & World English dictionary