Sentence examples for a mermaid from inspiring English sources

The phrase "a mermaid" is correct and usable in written English.
You can use it when referring to a mythical sea creature that is typically depicted as having the upper body of a woman and the lower body of a fish.
Example: "In the story, the sailor fell in love with a mermaid who saved him from drowning."
Alternatives: "a sea nymph" or "a water spirit".