nonrigid or semirigid airship dependent on internal gas pressure to maintain its form. The origin of the name blimp is uncertain, but the most common explanation is that it derives from “British Class B airship” plus “limp”—i.e., nonrigid. Blimps were used by navies during World War I in convoy and antisubmarine patrol duty, became attractions at fairs and expositions, and later carried advertising messages.