WordNet (r) 3.0 (2006):

block out
    v 1: plan where and when songs should be inserted into a
         theatrical production, or plan a theatrical production in
         general
    2: prevent from entering; "block out the strong sunlight" [syn:
       screen, block out]
    3: shield from light [syn: mask, block out]
    4: indicate roughly; "We sketched out our plan"

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "block out":
   adumbrate, block in, brief, carve, cast, chalk out, characterize,
   chisel, close, create, cut, delineate, detail, draft, efform,
   enumerate, fashion, figure, fix, forge, form, formalize, found,
   frame, hew, itemize, knead, knock out, lay out, lick into shape,
   line, mint, model, mold, number, obstruct, outline, parse, resolve,
   rough in, rough out, roughcast, roughhew, scan, schematize, sculpt,
   sculpture, set, shape, shroud, shut off, shut out, skeleton,
   sketch, stamp, tailor, thermoform, trace, work