phlegm

noun

ˈflem 

1

: viscid mucus secreted in abnormal quantity in the respiratory passages

2

: the one of the four humors (see humor sense 2c) in ancient and medieval physiology that was believed to be cold and moist and to cause lethargy and dullness

3

a

: dull or apathetic coldness or indifference

b

: intrepid coolness or calm fortitude

phlegmy

ˈfle-mē 

adjective

Synonyms

• numbness
• impassiveness
• impassivity
• emptiness
• coldness
• apathy

Examples of phlegm in a Sentence

He displayed remarkable phlegm in very dangerous conditions.

a man of remarkable phlegm, never showing enthusiasm nor displeasure

Recent Examples on the Web

Those sacs of air fill with fluid or pus, causing a cough with phlegm or pus, fever, chills and trouble breathing, according to the clinic. —Rebecca Cohen, NBC news, 16 Oct. 2025

With just enough codeine to wash the phlegm away, Veeze folds slapstick one-liners into audacious flexes like origami. —Pitchfork, 30 Sep. 2025

The second is having either 10 or more pack years of smoking, or symptoms of cough, phlegm and trouble breathing. —Katia Hetter, CNN Money, 28 Aug. 2025

Diagnosis of Legionnaires’ disease is made via chest X-ray, urine test and lab analysis of a phlegm sample. —Melissa Rudy, FOXNews.com, 20 Aug. 2025

Word History

Etymology

Middle English fleume, fleem, flemne "one of the four humors, temperament in which this humor is predominant (alleged to cause indolence or stolidity), bodily discharge, mucus," borrowed from Anglo-French fleume, flume, flegme (continental Old French flegme), borrowed from Late Latin phlegmat-, phlegma, borrowed from Greek phlegmat-, phlégma "flame, fire, inflammation, one of the four humors, white or colorless body secretion (as mucus, saliva)," from phleg-, stem of phlégein "to burn up, consume, kindle, fire up, (intransitive) blaze, gleam" + -mat-, -ma, resultative noun suffix; *phleg- going back to Indo-European *b^hleg- "shine, be bright," whence also, with varying ablaut, Germanic *blak- "flash, shine, burn" (see black entry 1), Latin fulgō, fulgere, later fulgeō, fulgēre "to shine brightly, flash, lighten" (< *b^hl̥g-), Tocharian B palkäṃ "shines," pälketär "burns, glows"

First Known Use

13th century, in the meaning defined at sense 2

Rhymes for phlegm

• clem
• em
• femme
• gem
• hem
• rem
• stem
• them
• atm
• chernozem
• diadem
• ibidem

Kids Definition

phlegm

noun

ˈflem 

1

: thick mucus produced in abnormal quantity in the respiratory passages

2

a

: cold indifference

b

: calm fortitude

phlegmy

ˈflem-ē 

adjective

Medical Definition

phlegm

noun

ˈflem 

1

: viscid mucus secreted in abnormal quantity in the respiratory passages

2

: the one of the four humors (see humor sense 2) of ancient and medieval physiology that was believed to be cold and moist and to cause lethargy and dullness