a ewe is a female sheep since the word is pronounced 'you' there is some confusion surrounding this word strictly from spelling 'an ewe' seems more appropriate but from a pronunciation point of view 'a ewe' is superior while i'm not sure which version is more gramatically correct a google search suggests that 'a ewe' is more common oddly some websites use both methods of spelling so i'm inclined to keep it at 'a ewe'