gender bender

Short definition from Wiktionary

Noun

1. 1
   A person who dresses in the clothes of another sex, or in clothes which make their gender identity ambiguous.
2. 2
   An event where people are encouraged to dress in the clothes of another sex, even if they would normally not.
3. 3
   A person capable of changing their physical sex.
4. 4
   An instance of someone's physical sex being changed, usually via magic.
5. 5
   Alternative form of gender bender.