In many countries, airships are also known as dirigibles from the French dirigeable, meaning "steerable." The first airships were called dirigible balloons. Over time, the word balloon was dropped from the phrase.
Allright, why were other early airships called 'blimps'?
(I thought the term 'dirigible' referred to non-rigid airships ie those where the shape of the envelope was derived by the gas pressure inside, rather than a framework of girders like R100/Hindenburgh, or have I got it the wrong way round?)