Definition of swap horses:
(n) :
Any of the small marine fish of the genus Hippocampus that have a horselike head and swim upright.
(n) :
(mythology) Synonym of hippocampus.
(n) :
(philately) Any of a series of high-value British stamps issued during the reign of King George V, featuring a depiction of Britannia on a chariot in choppy seas.
(n) :
(obsolete) The walrus.
(n) :
(obsolete) A hippopotamus.