merhorse

From mer- +‎ horse.

merhorse (plural merhorses)

1. (rare) A seahorse.
   • 1988, DeWitt Wallace; Lila Bell Acheson Wallace, The Reader's digest:

     […] super-otter, merhorse (a kind of sea horse), marine saurian and father-of-all-the-turtles.

   • 1998, Nigel Suckling; Bob Eggleton, The book of sea monsters:

     But there seems enough evidence to suggest that the merhorse may possibly be a distinct and genuine species. The creature is described as […] but there was no reappearance. A local expert was of the opinion that it was a 'real sea-horse'.

2. A mythical sea monster with a horse-like head, mane, and large eyes.

• rehomers