outsider Syllabification: (out·sid·er)Pronunciation: /ˌoutˈsīdər/Translate outsider | into French | into German | into Italian | into Spanish Definition of outsider noun 1a person who does not belong to a particular group. a person who is not accepted by or who is isolated from society. 2a competitor, applicant, etc., thought to have little chance of success:he started as a rank outsider for the titleoutsider in other Oxford dictionaries Definition of outsider in the British & World English dictionary