What is "terimon"

Terimon (foaled 20 April 1986) was a British Thoroughbred racehorse and sire. His most successful year was 1991, when he won the International Stakes at York and was named European Champion Older Horse at the inaugural Cartier Racing Awards. He is best known, however, for his performance in the 1989 Derby in which he finished second at odds of 500/1, the longest ever recorded for a placed horse in the race.