Laughing falcon (Zool.), a South American hawk (Herpetotheres cachinnans); -- so called from its notes, which resemble a shrill laugh. --
Laughing gas (Chem.), nitrous oxide, also called hyponitrous oxide, or protoxide of nitrogen; -- so called from the exhilaration and laughing which it sometimes produces when inhaled. It has been much used as an anaesthetic agent, though now its use is primarily in dentistry --
Laughing goose (Zool.), the European white-fronted goose. --
Laughing gull. (Zool.) (a) A common European gull (Xema ridibundus); -- called also pewit, black cap, red-legged gull, and sea crow. (b) An American gull (Larus atricilla). In summer the head is nearly black, the back slate color, and the five outer primaries black. --
Laughing hyena (Zool.), the spotted hyena. See Hyena. --
Laughing jackass (Zool.), the great brown kingfisher (Dacelo gigas), of Australia; -- called also giant kingfisher, and gogobera. --
Laughing owl (Zool.), a peculiar owl (Sceloglaux albifacies) of New Zealand, said to be on the verge of extinction. The name alludes to its notes. [ 1913 Webster ]

When he talked, he talked nonsense, and made himself the laughingstock of his hearers. Macaulay. [ 1913 Webster ]