What is Eighth ?
Eighth is , 8th adj, (noun) referring to 8 The eighth of February or February the eighth (February 8th). King Henry the Eighth (Henry VIII) had six wives. His eighth birthday is next Monday. (NOTE: eighth is usually written 8th in dates: April 8th, 1999; September 8th, 1866 (Americanstyle is September 8, 1866), say ‘the eighth of September’ or ‘September the eighth’ (Americanstyle is ‘September eighth’); with names of kings and queens, eighth is usually written VIII: King Henry VIII, say: ‘King Henry the Eighth’.)
source: Easier English, Student Dictionary Upper Intermediate Level