The Collaborative International Dictionary of English v.0.48:

Overburden \O`ver*bur"den\, v. t.
   To load with too great weight or too much care, etc. --Sir P.
   Sidney.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overburden \O"ver*bur`den\, n.
   The waste which overlies good stone in a quarry. --Raymond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overburden
    n 1: the surface soil that must be moved away to get at coal
         seams and mineral deposits
    2: an excessive burden [syn: overload, overburden]
    v 1: burden with too much work or responsibility
    2: load with excessive weight

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "overburden":
   bear hard upon, burden, burthen, charge, choke, congest, cram,
   crowd, cumber, drench, encumber, freight, glut, gluttonize,
   go hard with, go ill with, gorge, hamper, handicap, jam, jam-pack,
   lade, lie on, load, oppress, overcharge, overfeed, overfill,
   overlade, overload, overstuff, overtax, overweigh, overweight,
   pack, press hard upon, rest hard upon, saddle, satiate, saturate,
   soak, stuff, supercharge, supersaturate, surcharge, surfeit, tax,
   try one, weigh down, weigh heavy on, weigh on, weigh upon