effusion

noun

ef·​fu·​sion i-ˈfyü-zhən 

e-

1

: an act of effusing

2

: unrestrained expression of words or feelings

greeted her with great effusion

—Olive H. Prouty

3

a(1)

: the escape of a fluid from anatomical vessels by rupture or exudation

(2)

: the flow of a gas through an aperture whose diameter is small as compared with the distance between the molecules of the gas

b

: the fluid that escapes

Examples of effusion in a Sentence

Her poetic effusions became tiresome.

Recent Examples on the Web

Pleural effusion: Pleural effusion occurs as a complication of bacterial pneumonia when fluid builds up between the lungs and chest wall. —Lindsay Curtis, Health, 13 Apr. 2025

Mamdani facilitated this energy, working the line, oscillating between rousing effusions on the cost of living and flashing a goofy, impish grin. —Paula Aceves, Curbed, 8 Mar. 2025

Relegated in their time to Oscar-night footnotes, they have long since been recognized as his towering twin peaks—cinematic effusions of a dark, visionary, and fundamentally inimitable strangeness, against which the sheen of even a good Oscars ceremony pales. —Justin Chang, The New Yorker, 3 Mar. 2025

This week, lava fountains from Kilauea's north vent reached heights of 330 feet during the early hours of the eruption, with a slow effusion of lava from the south vent later. —Jeanine Santucci, USA TODAY, 14 Feb. 2025

Word History

Etymology

Middle English effusioun "emission, shedding," borrowed from Anglo-French effusiun, borrowed from Latin effūsiōn-, effūsiō, from effud-, variant stem of effundere "to pour out, discharge, expend" + -tiōn-, -tiō, suffix of action nouns — more at effuse entry 1

First Known Use

15th century, in the meaning defined at sense 1

Rhymes for effusion

• allusion
• collusion
• conclusion
• confusion
• contusion
• delusion
• diffusion
• exclusion
• extrusion
• illusion
• inclusion
• infusion

Kids Definition

effusion

noun

ef·​fu·​sion i-ˈfyü-zhən 

e-

1

: free expression of words or feelings

2

a

: escape of a fluid from containing vessels

b

: the fluid that escapes

Medical Definition

effusion

noun

ef·​fu·​sion i-ˈfyü-zhən, e- 

1

a

: the escape of a fluid from anatomical vessels by rupture or exudation

b

: the flow of a gas through an aperture whose diameter is small as compared with the distance between the molecules of the gas

2

: the fluid that escapes by extravasation see pleural effusion