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

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

Furthermore, unlike in the present day, in the 19th century those who received a Valentine were expected to send one in return, which meant there were also cards to discourage future attentions, recommend patience, express thanks, proclaim mutual admiration, or affirm love’s effusions. —Christopher Ferguson, The Conversation, 12 Feb. 2025

There are over 60 causes of pleural effusions, although the vast majority are due to heart failure, cancer, pneumonia (lung infection), and pulmonary embolism (blood clot in the lung).12 Breathlessness (dyspnea) is the hallmark symptom of pleural effusion. —Soma Mandal, Verywell Health, 4 Feb. 2025

Otitis Media With Effusion (Glue Ear) Otis media with effusion (OME), sometimes called glue ear, is a common condition, particularly in children ages 1-6. —Sherri Gordon, Health, 30 Dec. 2024

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