say it: MUR-man
merman is a noun meaning "United States singer who appeared in several musical comedies (1909-1984)". It carries 2 recorded senses.
United States singer who appeared in several musical comedies (1909-1984)
half man and half fish; lives in the sea
Forms marked are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for merman come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.