dyke BrE AmE , dike /daɪk/ noun [countable]
[ Sense 1, 3: Language: Old English ; Origin: dic 'ditch, dike' ]
[ Sense 2: Date: 1900-2000 ; Origin: Probably from morphadyke 'male and female person, homosexual' (1900-2000) , from hermaphrodite ]
1 . a wall or bank built to keep back water and prevent flooding
2 . taboo informal an offensive word for a ↑ lesbian (=woman who is sexually attracted to women) . Do not use this word.
3 . especially British English a narrow passage to carry water away SYN ditch