The Collaborative International Dictionary of English v.0.48:

Chuckle \Chuc"kle\, v. t. [imp. & p. p. Chuckled; p. pr. & vb.
   n. Chuckling.] [From 1st Chuck.]
   1. To call, as a hen her chickens; to cluck. [Obs.] --Dryden.
      [1913 Webster]

   2. To fondle; to cocker. [Obs.] --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chuckle \Chuc"kle\, n.
   A short, suppressed laugh; the expression of satisfaction,
   exultation, or derision.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chuckle \Chuc"kle\, v. i. [From 1st Chuck.]
   To laugh in a suppressed or broken manner, as expressing
   inward satisfaction, exultation, or derision.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chuckle
    n 1: a soft partly suppressed laugh [syn: chortle, chuckle]
    v 1: laugh quietly or with restraint [syn: chuckle, chortle,
         laugh softly]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "chuckle":
   Homeric laughter, be in stitches, belly laugh, boff, boffola,
   break up, burst into laughter, burst of laughter, burst out,
   burst out laughing, burst with laughter, bust a gut, cachinnate,
   cachinnation, cackle, chortle, convulsion, crow, crowing,
   fit of laughter, gales of laughter, giggle, go into convulsions,
   guffaw, ha-ha, hearty laugh, hee-haw, hee-hee, hilarity, ho-ho,
   horselaugh, laugh, laugh it up, laugh outright, laughing, laughter,
   nearly die laughing, outburst of laughter, peal of laughter,
   risibility, roar, roar of laughter, roar with laughter,
   shake like jelly, shake with laughter, shout, shout of laughter,
   shriek, snicker, snigger, sniggering, sniggle, snort, split,
   split with laughter, tee-hee, titter, yuck, yuk-yuk