flare
n. C / Un. a sudden, bright light that lasts for a short time. You often use it as a signal for help or to light up a dark area.
n. a sudden burst of bright light or flame, often used as a distress signal or for illumination. In photography, refers to light scattering in a lens system, often reducing image contrast.
The stranded sailors fired a flare into the night sky.
The pilot dropped a flare to illuminate the landing strip during the emergency night flight.
The photographer adjusted the lens hood to prevent lens flare from the setting sun, which was washing out the details in the foreground.
Origin unknown, first recorded in the mid 16th century, probably related to Latin flagrō (“I burn”). Norwegian flara (“to blaze; to flaunt in gaudy attire”) has a similar meaning, but the English word predates it. Possibly related to Middle High German vlederen (“to flutter”), represented by modern German flattern. The noun is derived from the verb.
Countable when referring to the device or the specific flash of light; uncountable when referring to the general phenomenon of light spreading.