flash over

C1 formal intransitive

In simple words

When a fire suddenly explodes and fills an entire room with flames all at once.

Literal meaning: A flash (sudden, rapid light/flame) that goes over — covering an entire area at once.

Meanings

1 C1 formal

rare

(Firefighting/technical) For a fire to reach the stage where all combustible materials in an enclosed space ignite simultaneously.

"The investigators believe the blaze flashed over within seconds of the initial ignition."

2 C1 formal

rare

(Electrical) For electricity to jump across a gap or insulator, creating an arc.

"The power surge caused the current to flash over the insulator."

Usage notes

Primarily a technical firefighting and engineering term. The noun 'flashover' is the standard form. Rarely used outside emergency services, fire safety, and technical reporting contexts. ESL learners are most likely to encounter this in technical or news texts about fires.

Commonly used with

fire room building point temperature stage

Forms

Base

flash over

I/you/we/they

3rd person

flashes over

he/she/it

Past simple

flashed over

yesterday

Past participle

flashed over

have + pp

-ing form

flashing over

continuous

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Synonyms

ignite simultaneously explode engulf

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