SquibA squib is a small explosive about the size of a firecracker. It is often used to ignite a larger pyrotechnic explosive, such as a rocket engine. They are also widely used in the special effects industry to simulate a bullet hit on a person. A "damp squib" is literally one that fails to go off due to wetting, but the term is come into general use to mean anything that fails to meet expectations.
A Squib is a type of small sailboat originally designed in 1967.