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]