wildfire

UK: /ˈwaɪldfaɪə^r/ US: /ˈwaɪldˌfaɪr/ ,(wīld′fī^ər′)

WordReference Random House Learner's Dictionary of American English © 2026

wild•fire /ˈwaɪldˌfaɪr/   n. [countable]

1. a large fire that spreads rapidly and is hard to put out.

Idioms

2. like wildfire, very rapidly and with unchecked force:
   The rumor spread like wildfire.

WordReference Random House Unabridged Dictionary of American English © 2026

wild•fire  (wīld′fī^ər′), n. 

1. a highly flammable composition, as Greek fire, difficult to extinguish when ignited, formerly used in warfare.
2. any large fire that spreads rapidly and is hard to extinguish.
3. Meteorology sheet lightning, unaccompanied by thunder.
4. Meteorology the ignis fatuus or a similar light.
5. Plant Diseases a disease of tobacco and soybeans, characterized by brown, necrotic spots, each surrounded by a yellow band, on the leaves and caused by a bacterium, Pseudomonas tabaci.
6. Pathology erysipelas or some similar disease.

• Middle English wildefire, Old English wildfȳr. See wild, fire bef. 1000

Collins Concise English Dictionary © HarperCollins Publishers::

wildfire / ˈwaɪldˌfaɪə/ noun

1. a highly flammable material, such as Greek fire, formerly used in warfare
2. a raging and uncontrollable fire
3. anything that is disseminated quickly (esp in the phrase spread like wildfire)
4. another name for will-o'-the-wisp