A male or female who wears clothes that are stereotypically worn by the opposite sex.

For women, it is debatable whether in this day an age trousers/pants count as cross dressing.

Cross dressers are often put into the transgender group, however it is important to know that a cross dresser does not necessarily have body or gender dysphoria, and can be perfectly happy with their gender identity assigned at birth.

Most transgender individuals do not appreciate being called cross dressers as they consider themselves, and should be considered by others as the gender they are dressing as.
A transwoman wearing girl's clothes is not a cross dresser, nor is she a man in drag. She's just a woman.

Cross dressing can be a hobby or maybe just a fashion sense. Someone who cross dresses does not necessarily cross dress 24/7.

Cross dressing can also be found to be sexually attractive by some.

Someone who wears either items of clothing or complete outfits traditionally associated with the opposite sex. Most people who are called crossdressers are heterosexual males. Most women crossdress, but female crossdressing is considered normal.

A man who likes to dress up in pretty clothes, little skirts, stockings, make-up, jewelry. We like to dress up as women and enjoy all the things a woman does.

a guy that dresses in woman's clothing

the act of putting on some ones elses pants just to defecate in them without there knowledge and laugh when they put them on

A person who wears the clothing of the opposite sex, but he or she wears the clothing backwards in order to symbolize the outdated and repressive social norms of the past.

Someone who dresses in tacky clothing adorned by multiple crucifixes in an attempt to look like Madonna Ciccone in her 1980's music video "Like a Virgin".