firefly Meaning, Definition & Usage

  1. noun tropical American click beetle having bright luminous spots
    Pyrophorus noctiluca; fire beetle.
  2. noun nocturnal beetle common in warm regions having luminescent abdominal organs
    lightning bug.

WordNet

Fire"fly` noun
Wordforms
plural Fireflies
Definitions
  1. (Zoöl.) Any luminous winged insect, esp. luminous beetles of the family Lampyridæ. ✍ The common American species belong to the genera Photinus and Photuris, in which both sexes are winged. The name is also applied to luminous species of Elateridæ. See Fire beetle.

Webster 1913