Prefix
mer-
sea; marine; applied to beings that are fully or partly sea-creatures.
mercow, mermaid, merman, merswine, mersnake
mer-
(fantasy) Of, pertaining to, or associated with the realm of mermaids and mermen.
merlady, merfolk, merwife, mermonster
mer-
Alternative form of mero- (“part, partial”) used before a vowel