mol·​ly | \ ˈmä-lē How to pronounce molly (audio) \
variants: or less commonly mollie
plural mollies

Definition of molly

: any of various small, often brightly colored tropical fish (genus Poecilia) that are live-bearers found in fresh, brackish, or salt water and include several that are highly valued as aquarium fishes

First Known Use of molly

1933, in the meaning defined above

History and Etymology for molly

by shortening from New Latin Mollienisia, former genus name, from Comte François N. Mollien †1850 French statesman

Keep scrolling for more

Learn More about molly

Statistics for molly

Look-up Popularity

Time Traveler for molly

The first known use of molly was in 1933

See more words from the same year

Keep scrolling for more

More Definitions for molly


Mol·​ly | \ ˈmä-lē How to pronounce Molly (audio) \

Medical Definition of Molly

: the illicit drug ecstasy especially when in a powdered or crystalline form contained in a capsule Experts say Molly, though often touted as pure, is often mixed with other drugs and ingredients, perhaps even more than the Ecstasy of yesteryear.— Helena Oliveiro, The Atlanta Journal-Constitution, 8 June 2013

More from Merriam-Webster on molly

Rhyming Dictionary: Words that rhyme with molly Encyclopedia article about molly

Comments on molly

What made you want to look up molly? Please tell us where you read or heard it (including the quote, if possible).


a period when something is suspended

Get Word of the Day daily email!

Test Your Vocabulary

Summer 2019 Words of the Day Quiz

  • a-bowl-of-peach-sorbet-with-cut-peaches-next-to-it
  • Which is a synonym of desideratum?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Dictionary Devil

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!