firefly
n.a small beetle that glows with a soft light in the dark. You usually see them flying around on warm summer nights.
n.a nocturnal beetle of the family Lampyridae, characterised by the use of bioluminescence to attract mates or prey.
“The children tried to catch a firefly in a glass jar.”
“As the sun set over the meadow, hundreds of fireflies began to blink in the tall grass.”
“The rhythmic flashing of the firefly is not merely decorative; it serves as a sophisticated species-specific signal used to locate potential mates in the dense evening foliage.”
Commonly referred to as a 'lightning bug' in certain regional dialects of American English.
Endocentric compound of fire + fly, because the insects glow; whence also lightning bug. Compare glow fly, glowworm, and lanternfly.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.