Firefly (noun)

1. A nocturnal beetle of the family Lampyridae, typically having a soft body and capable of producing light from specialized structures on the abdomen.
2. Any of various other insects, such as certain click beetles, that are able to produce light.

Origin:

Late 17th century: from fire + fly.

Examples:

1. He watched the fireflies dancing in the summer night sky.
2. The fireflies were attracted to the porch light.
3. The firefly's light is created through a chemical reaction in their abdomens.
4. Fireflies are a common sight in many parts of the world during the summer months.
5. She captured the firefly in a jar to observe it up close.