The Collaborative International Dictionary of English v.0.48:

Eaves \Eaves\, n. pl. [OE. evese, pl. eveses, AS. efese eaves,
   brim, brink; akin to OHG. obisa, opasa, porch, hall, MHG.
   obse eaves, Icel. ups, Goth. ubizwa porch; cf. Icel.
   upsar-dropi, OSw. ops[aum]-drup water dropping from the
   eaves. Probably from the root of E. over. The s of eaves is
   in English regarded as a plural ending, though not so in
   Saxon. See Over, and cf. Eavesdrop.]
   1. (Arch.) The edges or lower borders of the roof of a
      building, which overhang the walls, and cast off the water
      that falls on the roof.
      [1913 Webster]

   2. Brow; ridge. [Obs.] "Eaves of the hill." --Wyclif.
      [1913 Webster]

   3. Eyelids or eyelashes.
      [1913 Webster]

            And closing eaves of wearied eyes.    --Tennyson.
      [1913 Webster]

   Eaves board (Arch.), an arris fillet, or a thick board with
      a feather edge, nailed across the rafters at the eaves of
      a building, to raise the lower course of slates a little,
      or to receive the lowest course of tiles; -- called also
      eaves catch and eaves lath.

   Eaves channel, Eaves gutter, Eaves trough. Same as
      Gutter, 1.

   Eaves molding (Arch.), a molding immediately below the
      eaves, acting as a cornice or part of a cornice.

   Eaves swallow (Zo["o]l.).
      (a) The cliff swallow; -- so called from its habit of
          building retort-shaped nests of mud under the eaves of
          buildings. See Cliff swallow, under Cliff.
      (b) The European swallow.
          [1913 Webster]

WordNet (r) 3.0 (2006):

eaves
    n 1: the overhang at the lower edge of a roof

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "eaves":
   ceiling, housetop, lantern, overhead, penthouse, plafond,
   ridgepole, roof, roof garden, roof-deck, roofage, roofing,
   roofpole, rooftop, rooftree, shingles, skylight, slates, tiles,
   top