The word ‘bolide‘ [boh-lahyd] comes from the Greek ‘bolis,’ which can mean ‘missile’ or ‘to flash.’ The International Astronomical Union (IAU) has no official definition of ‘bolide,’ and generally considers the term synonymous with ‘fireball,’ a brighter-than-usual meteor. The IAU defines a fireball as ‘a meteor brighter than any of the planets’ (magnitude −4 or greater). Astronomers tend to use ‘bolide’ to identify an exceptionally bright fireball (magnitude −14 or brighter), particularly one that explodes (sometimes called a detonating fireball).
It may also be used to mean a fireball which creates audible sounds. If the magnitude of a bolide reaches −17 or brighter it is known as a ‘superbolide.’ Geologists use the term ‘bolide’ more often than astronomers do: in geology it indicates a very large impactor. For example, the U.S. Geological Survey uses the term to mean a generic large crater-forming projectile ‘to imply that we do not know the precise nature of the impacting body … whether it is a rocky or metallic asteroid, or an icy comet, for example.’
The Daily Omnivore 
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