The Collaborative International Dictionary of English v.0.48:

Laugh \Laugh\ (l[aum]f), v. i. [imp. & p. p. Laughed
   (l[aum]ft); p. pr. & vb. n. Laughing.] [OE. laughen,
   laghen, lauhen, AS. hlehhan, hlihhan, hlyhhan, hliehhan; akin
   to OS. hlahan, D. & G. lachen, OHG. hlahhan, lahhan,
   lahh[=e]n, Icel. hl[ae]ja,W Dan. lee, Sw. le, Goth. hlahjan;
   perh. of imitative origin.]
   1. To show mirth, satisfaction, or derision, by peculiar
      movement of the muscles of the face, particularly of the
      mouth, causing a lighting up of the face and eyes, and
      usually accompanied by the emission of explosive or
      chuckling sounds from the chest and throat; to indulge in
      laughter.
      [1913 Webster]

            Queen Hecuba laughed that her eyes ran o'er. --Shak.
      [1913 Webster]

            He laugheth that winneth.             --Heywood's
                                                  Prov.
      [1913 Webster]

   2. Fig.: To be or appear gay, cheerful, pleasant, mirthful,
      lively, or brilliant; to sparkle; to sport.
      [1913 Webster]

            Then laughs the childish year, with flowerets
            crowned.                              --Dryden.
      [1913 Webster]

            In Folly's cup still laughs the bubble Joy. --Pope.
      [1913 Webster]

   To laugh at, to make an object of laughter or ridicule; to
      make fun of; to deride.
      [1913 Webster]

            No wit to flatter left of all his store,
            No fool to laugh at, which he valued more. --Pope.


   To laugh in the sleeve, To laugh up one's sleeve, to
      laugh secretly, or so as not to be observed, especially
      while apparently preserving a grave or serious demeanor
      toward the person or persons laughed at.

   To laugh out, to laugh in spite of some restraining
      influence; to laugh aloud.

   To laugh out of the other corner of the mouth or To laugh
   out of the other side of the mouth, to weep or cry; to feel
      regret, vexation, or disappointment after hilarity or
      exaltation. [Slang]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Laughing \Laugh"ing\, a. & n.
   from Laugh, v. i.
   [1913 Webster]

   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]

WordNet (r) 3.0 (2006):

laughing
    adj 1: showing or feeling mirth or pleasure or happiness;
           "laughing children" [syn: laughing(a), riant]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "laughing":
   Homeric laughter, beaming, beatific, beatified, belly laugh,
   blessed, blissful, blithe, blithesome, boff, boffola, bright,
   bright and sunny, burst of laughter, cachinnation, cackle,
   capering, cheerful, cheery, chirping, chortle, chuckle, convulsion,
   crow, dancing, elated, eupeptic, euphoric, exalted, exhilarated,
   fit of laughter, flushed, flushed with joy, gales of laughter, gay,
   genial, giggle, glad, gladsome, glowing, guffaw, ha-ha, happy,
   hearty laugh, hee-haw, hee-hee, high, hilarity, ho-ho, hopeful,
   horselaugh, in good spirits, in high spirits, irrepressible,
   joyful, joyous, laugh, laughter, leaping, of good cheer,
   optimistic, outburst of laughter, peal of laughter, pleasant,
   purring, radiant, riant, risibility, roar of laughter, rosy,
   sanguine, sanguineous, shout, shout of laughter, shriek, singing,
   smiling, smirking, snicker, snigger, snort, sparkling, starry-eyed,
   sunny, tee-hee, thrice happy, titter, winsome, yuck, yuk-yuk