painkiller Syllabification: (pain·kil·ler)Pronunciation: /ˈpānˌkilər/Translate painkiller | into French | into German | into Italian | into Spanish Definition of painkiller noun a drug or medicine for relieving pain. Derivatives painkillingPronunciation: /-ˌkiliNG/ adjective painkiller in other Oxford dictionaries Definition of painkiller in the British & World English dictionary