(a) A man who is comfortable with or embraces typical working-class dress, usually work clothes, that have changed very little over the years.
(b) A man, usually a young man, who enjoys dressing up but in the outmoded 'square' fashions of the Fifties and early Sixties.
(a) Tom dresses like a bear but he's not gay. In that flannel shirt, work jeans and lace-up boots, he's classically retrosexual.
(b) Jeff loves to scout out fedoras, slim ties and Ivy-League cut suits. The more he looks like Frank Sinatra in the late Fifties or a character from TV's MAD MEN in the early Sixties, he is really pushing the retrosexual button.