Real Dictionary

flare
countable noun: A flare is a small device that produces a bright flame. Flares are used as signals, for example on ships.
verb: If a fire flares, the flames suddenly become larger.

flare in American English
a bright, unsteady blaze of light lasting only a little while; outburst of flame
to blaze up with a sudden, bright light
to make flare
intransitive verb: to burn with an unsteady, swaying flame, as a torch or candle in the wind
transitive verb: to cause (a candle, torch, etc.) to burn with a swaying flame

flare in British English
noun: an unsteady flame
verb: to burn or cause to burn with an unsteady or sudden bright flame

flare in Chemical Engineering
noun: A flare is a flame used for burning flammable waste gases to get rid of them.

flare in the Oil and Gas Industry
verb: To flare unwanted gas at an oil well is to get rid of it by burning it.