From Longman Dictionary of Contemporary Englishfly halfˌfly ˈhalf noun [countable] DSOa player in a game of rugby. A fly half has to be able to run quickly.
Examples from the Corpus
fly half• Mark Trodden comes in at fly half.• Influential fly half and captain Michael Lynagh is out for six weeks with a dislocated left shoulder.• Smith and Hannaford teaming up again with fly half, Neil Matthews diving in. 