What’s the difference between a dirigible and a blimp?
They have the same general form, but you don’t want to be misled. It’s tempting to assume, as I did for so many years, that the difference between the airships is visible when they’re deflated: a dirigible is rigid and a blimp is limp. It just seems so obvious, no?
Obvious but wrong. Similarity is not identity. Hydrogen and helium can both keep an airship aloft, but if you choose the wrong one you can go down in flames.
The truth is that a blimp is a dirigible. But not all dirigibles are blimps.
One may be forgiven for seeing rigid in dirigible, but I can see gerbil in it too and yet I am confident that airships are not held aloft by rodents running on wheels. Likewise, the presence of dirge, bridge, and bilge in it do not guarantee funereality, traversivity, or seawater. To find the origin of the word you must look in the right direction.
The right direction is direction itself – specifically the Latin word (and etymological origin) for it: dirigere. Something (in fact anything) that is dirigible is capable of being directed – i.e., steered. This is what all those cigar-shaped, finned, lighter-than-air vessels have in common, be they rigid (like Zeppelins – a brand name, by the way), semi-rigid, or blimps: unlike the classic “balloon-shaped” balloons, they can be steered and propelled. They are not merely at the mercy of the winds.
A blimp, then, is a kind of dirigible that does not have a rigid framework. Deflate it and it will be limp. So of course it is tempting to assume that the limp in blimp is the limp in, well, limp. There are even stories about how the word came to be, such as that the airship was “Type B: Limp.” Alas, there is a striking lack of actual historical evidence for limp-based accounts. At least as likely are accounts linking it to the sound it makes when struck with the hand, or other more impressionistic sound-symbolic explanations. But no one’s entirely sure. Yet.
What we do know is that the word blimp showed up during World War I, when the things it names did. Of course, coming up with the ability to fly, we soon look to it for ways to hurt other people, for example by dropping bombs from above. Now, though, we have even more efficient and effective ways of killing people, so the place you’re most likely to see a blimp is floating above a sporting event – the continuation of way by other means. And actually the current Goodyear airship is the continuation of blimps by other means: it is an airship, and a dirigible one, but it is actually a semi-rigid airship made by Zeppelin.
So be wary of relying on forms! They may be nothing but hot air. They may be limp. They may be misdirecting you.