Short for 'dirigible
balloon'. Whilst not specifically different from a
blimp (which might also be dirigible, in the Websterian sense), common usage usually denotes an
airship with a rigid internal structure, whereas the blimp relies on the pressure of the
buoyant gas to maintain its shape.
Every monocle-adorned supervillain should have one of these, allowing for a dramatic escape to a secret base in a far-off caldera, waiting for The Right Time To Return For Vengeance (also known as the sequel).
It should be noted that it probably was the fabric cover, and not the hydrogen that caused the Hindenburg disaster. Samples of the fabric cover were shown to be rather susceptible to an electric arc (mimicking the weather conditions at the time of the disaster) - the sample ignited and was completely consumed by fire in seconds, after sixty years of storage.
Source: Jacquelyn Cochran Bokow - Hydrogen Exonerated in Hindenburg Disaster, found at http://www.ttcorp.com/nha/advocate/ad22zepp.htm