1. Thick, sticky, stringy mucus secreted by the mucous membrane of the respiratory tract, as during a cold or other respiratory infection.
2. One of the four humors of ancient and medieval physiology, thought to cause sluggishness, apathy, and evenness of temper.
3. Sluggishness of temperament.
4. Calm self-possession; equanimity.
[Middle English fleume, mucous discharge, the humor phlegm, from Old French, from Medieval Latin phlegma, flegma, from Late Latin phlegma, the humor phlegm, from Greek, heat, the humor phlegm, from phlegein, to burn.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2016 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus