limp v.

"non-rigid airship," 1916, of obscure origin, with many claimants (even J.R.R. Tolkien had a guess at it). "One of the weird coinages of the airmen" [Weekley]. Common theory (which dates to 1919) is that it is from the designers' prototype nickname Type B-limp, in the sense of "without internal framework," as opposed to Type A-rigid; thus see limp (adj.), but references are wanting. There apparently was a type b in the U.S. military's development program for airships in World War I.

late 14c., "edge of a quadrant or other instrument," from Latin limbus "ornamental border, hem, fringe, edge," a word of uncertain origin. Klein suggests it is cognate with Sanskrit lambate "hang down limply" and English limp (adj.). Tucker writes that "the sense appears to be that of something which twists, goes round, or binds ... not of something which hangs loose," and suggests cognates in Lithuanian linta "ribbon," Old Norse linnr "whether." De Vaan tends to agree with Klein and writes, "In view of the phoneme *b, the very specific meaning of limbus and its absence from the oldest literature, the etymology remains uncertain." Astronomical sense of "edge of the disk of a heavenly body" first attested 1670s. Related: Limbal.