[ih-ruhp-shuh n]


an issuing forth suddenly and violently; outburst; outbreak.
Geology. the ejection of molten rock, steam, etc., as from a volcano or geyser.
something that is erupted or ejected, as molten rock, volcanic ash, or steam.
  1. the breaking out of a rash or the like.
  2. a rash or exanthem.

Origin of eruption

1375–1425; late Middle English < Latin ēruptiōn- (stem of ēruptiō). See erupt, -ion
Related formse·rup·tion·al, adjectivenon·e·rup·tion, nounpre·e·rup·tion, nounre·e·rup·tion, noun
Can be confusederuption irruption Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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Word Origin and History for eruption

early 15c., from Middle French éruption (14c.) and directly from Latin eruptionem (nominative eruptio) "a breaking out," noun of action from past participle stem of erumpere "break out, burst forth," from ex- "out" (see ex-) + rumpere "to break, rupture" (see rupture (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper

eruption in Medicine




An appearance of a rash or blemish on the skin.
Such a rash or blemish.
The emergence of a tooth through the gums.
Related formse•ruptive (-tĭv) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

eruption in Science



The release of gas, ash, molten materials, or hot water into the atmosphere or onto the Earth's surface from a volcano or other opening in the Earth's surface.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.