Merman
/ˈmɜːrmæn/
Definition 1 of 1
Pro Tip 1/3Mythical Origins
Mermen are rooted in mythology, so they're often found in stories involving magic and the supernatural. 
The ancient scrolls described a merman guarding a sunken treasure.
Pro Tip 2/3Literary Device
Mermen can symbolize allure and danger of the unknown, particularly in maritime folklore. 
The sailors feared the siren's song, lest a merman drag them to the ocean's depths.
Pro Tip 3/3Gender Specific
A 'merman' refers specifically to the male version of the half-human, half-fish creature, with 'mermaid' being the female counterpart. 
Ariadne was shocked to encounter not a mermaid, but a merman, under the waves.