The Collaborative International Dictionary of English v.0.48:

Overspread \O`ver*spread"\, v. t. [imp. & p. p. Overspread; p.
   pr. & vb. n. Overspreading.] [AS. oferspr[=ae]dan.]
   To spread over; to cover; as, the deluge overspread the
   earth. --Chaucer.
   [1913 Webster]

         Those nations of the North
         Which overspread the world.              --Drayton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overspread \O`ver*spread"\, v. i.
   To be spread or scattered over.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overspread
    v 1: spread across or over; "A big oil spot spread across the
         water" [syn: spread, overspread]

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "overspread":
   apply to, beset, bespread, bestrew, blanket, block, broadcast,
   canopy, cap, circumfuse, cloak, clothe, cloud, cope, cover,
   cover up, cowl, crawl with, creep with, crown, curtain, deal out,
   diffract, diffuse, dispense, disperse, dispread, disseminate,
   distribute, diverge, eclipse, extend throughout, fan out, fill,
   film, flood, grow over, honeycomb, hood, imbue, infest, invade,
   issue, know no bounds, lay on, lay over, leave no void, leaven,
   luxuriate, mantle, mask, muffle, obduce, obscure, occult, occupy,
   overabound, overbrim, overcast, overflow, overgrow, overgrown,
   overlay, overrun, overscatter, oversow, overspill, overswarm,
   penetrate, permeate, pervade, plague, propagate, publish,
   pullulate, put on, radiate, ravage, retail, run riot, run through,
   scatter, screen, scum, shield, sow, sow broadcast, spill over,
   splay, spread, spread out, spread over, strew, suffuse,
   superabound, superimpose, superpose, swarm, swarm over, swarm with,
   teem, teem over, teem with, transfuse, utter, veil