The term used to describe a fan(usually of the older kind, male or female) of the show My Little Pony: Friendship is Magic.
It is the combination of the words 'bro' and 'pony'
Although 'bro' may refer to males, the term 'brony' is gender-neutral, and thus it may be applied to the male and female fans of the show.
"Brony" is the singular form of "Bronies
The term was coined on 4chan's /co/ board.