Transvestism refers to a paraphilia in which a heterosexual man dresses in women's clothing as his primary means of becoming sexually aroused.
It is the practice of deriving sexual gratification from dressing as a member of the other gender.
Other /More definition:
Transvestism means dressing in the clothing of the opposite sex. Transvestism is distinct from both Transsexualism and Homosexuality. In Psychiatry, Transvestism can be considered a Paraphilia.
Transvestism is also known as Cross-dressing.