WordReference Random House Unabridged Dictionary of American English © 2026
e•rup•tion
(i rup′shən),USA pronunciation n.
e•rup′tion•al, adj.
- an issuing forth suddenly and violently;
outburst;
outbreak. - Geologythe ejection of molten rock, steam, etc., as from a volcano or geyser.
- Geologysomething that is erupted or ejected, as molten rock, volcanic ash, or steam.
- Pathology
- the breaking out of a rash or the like.
- a rash or exanthem.
- Latin ēruptiōn- (stem of ēruptiō). See erupt, -ion
- late Middle English 1375–1425
'eruption' also found in these entries (note: many are not synonyms or translations):
Atlantis
- Castellammare di Stabia
- Herculaneum
- Koplik's spots
- Krakatau
- Krakatoa
- Montserrat
- Nevado del Ruiz
- Nios
- Paricutín
- Pele's tears
- Pelée
- Plymouth
- Pompeii
- Rocky Mountain spotted fever
- Saint-Pierre
- Strombolian
- Tambora
- Tristan da Cunha
- Valley of Ten Thousand Smokes
- Vesuvius
- acne
- active
- anthema
- ash
- ash fall
- blotch
- break
- bump
- carbuncle
- chickenpox
- cold sore
- creeping eruption
- dentition
- efflorescence
- ejecta
- eruptive
- exanthem
- exanthema
- extinct
- gale
- ground itch
- herpes
- impacted
- impetigo
- malanders
- measles
- miliaria
- miliary
- nova