The Collaborative International Dictionary of English v.0.48:

overfill \o`ver*fill"\, v. t.
   To fill to excess; to surcharge.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overfill
    v 1: fill beyond capacity; "overfill the baskets"

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "overfill":
   allay, brim, charge, chock, choke, cloy, congest, cram, crowd,
   drench, engorge, fill, fill to overflowing, fill up, freight, glut,
   gluttonize, gorge, jade, jam, jam-pack, lade, load, overbrim,
   overburden, overcharge, overdose, overfeed, overgorge, overlade,
   overload, overrun, oversaturate, overstuff, overweight, pack, pad,
   pall, ram in, run, sate, satiate, satisfy, saturate, slake, soak,
   stuff, supercharge, supersaturate, surcharge, surfeit, top off,
   wad, weight