The Collaborative International Dictionary of English v.0.48:

petting \petting\ n.
   Sexually titillating foreplay without contact with the
   genital organs.

   Syn: caressing, cuddling, fondling, hugging, kissing,
        necking, smooching, snuggling.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Pet \Pet\, v. t. [imp. & p. p. Petted; p. pr. & vb. n.
   Petting.]
   To treat as a pet; to fondle; to indulge; as, she was petted
   and spoiled.
   [1913 Webster]

WordNet (r) 3.0 (2006):

petting
    n 1: affectionate play (or foreplay without contact with the
         genital organs) [syn: caressing, cuddling, fondling,
         hugging, kissing, necking, petting, smooching,
         snuggling]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "petting":
   amorous dalliance, billing and cooing, bundling, caressing,
   cuddling, dalliance, feeling, fingering, fondling, friction,
   frottage, handling, hugging, kissing, lollygagging, lovemaking,
   manipulation, necking, nestling, nuzzling, palpation, pressure,
   rubbing, sexual intercourse, snuggling, spooning, stroking,
   touching