"Mermaid" is a compound of mer, the French word for "sea", and maid, a girl or young woman. Though some movies show a male version of the mermaid, the merman, most mythology suggests that mermaids were only women and that there were no "mermen". 

                                                                                          

                      

                                                                                                                                          

Much like sirens, mermaids will sing to people or to gods to enchant them, distracting them from their work and causing people to walk off a ship's deck or to run their ship aground. Other stories depict mermaids squeezing the life out of drowning men while attempting to rescue them. They are also said to carry humans down to their underwater kingdoms. 

In Hans Christian Andersen's The Little Mermaid, it is said that mermaids forget that humans cannot breathe underwater, while other stories say they drown men out of spite, while still other fables portray mermaids as benevolent toward men. This singing chant is probably a curse to the mermaid as well.

       

The sirens of Greek mythology are sometimes portrayed in later folklore as mermaid-like; in fact, some languages use the same word for both bird and fish creatures, such as the Maltese word 'sirena'. Other related types of mythical or legendary creatures are water fairies (e.g., various water nymphs) and selkies, animals that can transform themselves from seals to humans.