Learn how to say Fireflies correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word firefly:
noun (plural fireflies)
a soft-bodied beetle related to the glow-worm, the winged male and flightless female of which both have luminescent organs. The light is chiefly produced in flashes and typically functions as a signal between the sexes.
Family Lampyridae: many species, especially in the tropics, and including the European Luciola lusitanica