Longman Dictionary of Contemporary English
The Collaborative International Dictionary
horseshow \horse"show`\, horse show \horse" show`\n. a competitive exhibition of horses.
Wikipedia
A horse show is a judged exhibition of horses and ponies. Many different horse breeds and equestrian disciplines hold competitions worldwide, from local to the international levels. Most horse shows run from one to three days, sometimes longer for major, all-breed events or national and international championships in a given discipline or breed. Most shows consist of a series of different performances, called classes, wherein a group of horses with similar training or characteristics compete against one another for awards and, often, prize money.
Usage examples of "horse show".
Burrich had warned me that some dishonest horse traders fed their charges carris oil on their grain, for the purpose of winning a race, or to make a sick horse show well at an auction.