Small insects that glow in the dark by producing light in their abdomens, common in summer evenings.
Compound word: 'fire' (Old English 'fyr') referring to the glow they produce, and 'flies' (Old English 'fleoge'), the insects. The name perfectly describes their characteristic bioluminescence.
Fireflies are actually beetles, not flies, and they use their glow to find mates in the dark—each species has its own unique blinking pattern like a biological morse code, and scientists can identify species just by watching their flash patterns.
Complete word intelligence in one call. Free tier — 50 lookups/day.