noun (plural mollies)
- a small live-bearing killifish which is popular in aquaria and has been bred in many colours, especially black.
- Genus Poecilia, family Poeciliidae: several species, in particular P. sphenops. See also sailfin molly
1930s: from modern Latin Mollienisia (former genus name), from the name of Count Mollien (1758–1850), French statesman