merchild

English

Etymology

From mer- +‎ child.

Noun

merchild (plural merchildren)

1. The young of either sex of a legendary creature, human from the waist up, fishlike from the waist down.
   • 1904, Thomas Bird Mosher, The Bibelot, p. 160:

     The fish-tailed merchild carved in crumbling stone
     Wreathed with loose straggling roses, reigns alone...