Gainor is an English name with Ancient Celtic origins. It is probably a derivative of the Celtic name 'Mag Fhionnbhairr', which means 'son of Finbar'. The name 'Finbar' itself is a Gaelic name, derived from the words 'fionn', which means 'fair', and 'barr', which means 'head'. The name could have started as a nickname for Norse Vikings because they had fair hair.