The Collaborative International Dictionary of English v.0.48:

Sieve \Sieve\, n. [OE. sive, AS. sife; akin to D. zeef, zift,
   OHG. sib, G. sieb. [root]151a. Cf. Sift.]
   1. A utensil for separating the finer and coarser parts of a
      pulverized or granulated substance from each other. It
      consist of a vessel, usually shallow, with the bottom
      perforated, or made of hair, wire, or the like, woven in
      meshes. "In a sieve thrown and sifted." --Chaucer.
      [1913 Webster]

   2. A kind of coarse basket. --Simmonds.
      [1913 Webster]

   Sieve cells (Bot.), cribriform cells. See under
      Cribriform.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sieve
    n 1: a strainer for separating lumps from powdered material or
         grading particles [syn: sieve, screen]
    v 1: examine in order to test suitability; "screen these
         samples"; "screen the job applicants" [syn: screen,
         screen out, sieve, sort]
    2: check and sort carefully; "sift the information" [syn:
       sieve, sift]
    3: separate by passing through a sieve or other straining device
       to separate out coarser elements; "sift the flour" [syn:
       sift, sieve, strain]
    4: distinguish and separate out; "sift through the job
       candidates" [syn: sieve, sift]

Moby Thesaurus II by Grady Ward, 1.0:

171 Moby Thesaurus words for "sieve":
   analyze, analyzer, arabesque, assort, basketry, basketwork, bolt,
   bolter, breaker, cancellation, categorize, centrifuge, clack,
   clarifier, clarify, classify, clear, colander, collate,
   contradistinguish, cordon, cordon off, cradle, cribble,
   cribriformity, cribrosity, cross-hatching, crossing-out, cull out,
   cutter, decrassify, demarcate, demark, depurate, differentiate,
   discriminate, distill, distinguish, divide, draw the line,
   edulcorate, elute, essentialize, extract, filigree, filter,
   filtrate, fret, fretwork, ghettoize, gin, gossiper, gradate, grade,
   grate, grating, grid, gridiron, grille, grillwork, group, hachure,
   hatching, honeycomb, insulate, interlacement, intertexture,
   intertwinement, isolate, keep apart, keep aside, lace, lacery,
   lacework, lacing, lattice, latticework, lay aside, leach,
   lixiviate, lixiviator, mark the interface, mesh, meshes, meshwork,
   net, netting, network, percolate, percolator, pick out, plexure,
   plexus, porosity, porousness, purifier, purify, put aside,
   quarantine, quidnunc, raddle, rank, rectify, refine, refiner,
   refinery, reticle, reticulation, reticule, reticulum, riddle,
   rocker, rumormonger, scandalmonger, screen, screen out, screening,
   seclude, segregate, select, separate, separator, set a limit,
   set apart, set aside, set off, sever, severalize, sieve out,
   sievelikeness, sift, sift out, sifter, size, sort, sort out,
   sorter, spiritualize, split hairs, sponge, strain, strainer,
   stripper, subdivide, sublimate, sublime, subordinate, subtilize,
   tabby, talebearer, texture, thrash, thresh, tissue, tracery,
   trellis, trelliswork, try, wattle, weave, weaving, web, webbing,
   webwork, weft, wicker, wickerwork, winnow, winnowing basket,
   winnowing fan, winnowing machine