transvestite

Short definition from Wiktionary

Noun

1. 1
   A person who sometimes wears clothes traditionally worn by and associated with the opposite sex; typically a male who cross-dresses occasionally by habit or personal choice.
2. 2
   A person, typically a heterosexual male, who compulsively seeks and derives paraphilic sexual arousal from cross-dressing, especially if the urges and behavior cause the patient distress or social impairment.
3. 3
   An animal that engages in sexual mimicry.