Wiktionary (0.00 / 0 votes) Rate this definition: squib (Noun). A small firework that is intended to spew sparks rather than explode. English Navy squibs set fire to two dozen enemy ships in a Dutch harbor during the 16th century battle against the Spanish Armada. squib (Noun). A similar device used to ignite an explosive or launch a rocket, etc. squib (Noun). Any small firecracker sold to the general public.