firefly

IPA/ˈfaɪəflaɪ/
KK[fˈaɪɚflˌaɪ]IPA/ˈfaɪərflaɪ/

firefly — noun

  • fireflysingular
  • firefliesplural

1. a small flying beetle that produces a flashing yellow-green light from the rear

1.nounA2
Definition

a small flying beetle that produces a flashing yellow-green light from the rear of its body, most often seen on warm evenings in summer

Example

On warm summer nights, the children caught fireflies and watched them glow in a jar.

catch + fireflies (verb-object collocation for capturing)

A firefly's flashing light helps it find a mate during the breeding season.

singular possessive: firefly's + light (noun as subject with 's)

Common collocations
  • catch fireflies
  • firefly flashes
  • firefly glows
  • watch fireflies
  • summer fireflies
Synonyms
  • lightning bug

    regional synonym used mainly in the southern and midwestern United States

  • glowworm

    usually refers to the wingless larval or female form of certain firefly species, not the adult flying insect

Usage Note

The firefly is a type of beetle, not a true fly. In some parts of the United States, it is also called a 'lightning bug'.

Common Mistakes

A firefly is a kind of fly.
A firefly is actually a beetle, not a fly.
Despite its name, the firefly belongs to the beetle family (Lampyridae), not the fly family.

Synonym discussion

Sense: noun/1

Firefly is the standard term worldwide for bioluminescent beetles of the family Lampyridae. Lightning bug is a common regional alternative in the southern and midwestern United States — it describes the same insect but emphasises the flashing quality of the light rather than the fire-like glow. Glowworm is more specific and often confusing: it typically refers to the wingless larval stage or the short-winged adult female of certain firefly species, which produce a steady glow rather than a flashing signal. If you see a flying insect blinking on and off at dusk, call it a firefly or lightning bug. If you see a slow, steady glow coming from the ground or a low plant, it may be a glowworm.

firefly ↗lightning bugglowworm

Common collocations

Nouns

Etymology

Old EnglishMiddle EnglishEnglish

A compound word formed from 'fire' and 'fly' (the insect). The word was first recorded in English around 1655 and describes the insect's ability to produce what looks like a tiny flame from its body. 'Fire' comes from Old English fȳr, and 'fly' comes from Old English flēoge, meaning a flying insect.

First known use

1655

1655, in the meaning defined above