tam-o'-shanterPronunciation: /ˌtaməˈʃantə/Definition of tam-o'-shanter noun a round woollen or cloth cap of Scottish origin, with a bobble in the centre. Origin: mid 19th century: named after the hero of Burns's poem Tam o' Shanter (1790)tam-o'-shanter in other Oxford dictionaries Definition of tam-o'-shanter in the US English dictionary