The Collaborative International Dictionary of English v.0.48:

Chock-full \Chock"-full`\ chockfull \chock"full`\, pred. a.
   Quite full; full to capacity; choke-full; as, chowder
   chock-full of clams.

   Syn: chockablock(predicate), chockful(predicate),
        choke-full(predicate), chuck-full(predicate), cram full.
        [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

chock-full
    adj 1: packed full to capacity; "chowder chockablock with pieces
           of fish" [syn: chockablock(p), chock-full,
           chockful, choke-full, chuck-full, cram full]