The Collaborative International Dictionary of English v.0.48:

Hearth \Hearth\ (h[aum]rth), n. [OE. harthe, herth, herthe, AS.
   heor[eth]; akin to D. haard, heerd, Sw. h[aum]rd, G. herd;
   cf. Goth. ha['u]ri a coal, Icel. hyrr embers, and L. cremare
   to burn.]
   1. The pavement or floor of brick, stone, or metal in a
      chimney, on which a fire is made; the floor of a
      fireplace; also, a corresponding part of a stove.
      [1913 Webster]

            There was a fire on the hearth burning before him.
                                                  --Jer. xxxvi.
                                                  22.
      [1913 Webster]

            Where fires thou find'st unraked and hearths
            unswept.
            There pinch the maids as blue as bilberry. --Shak.
      [1913 Webster]

   2. The house itself, as the abode of comfort to its inmates
      and of hospitality to strangers; fireside.
      [1913 Webster]

            Household talk and phrases of the hearth.
                                                  --Tennyson.

   3. (Metal. & Manuf.) The floor of a furnace, on which the
      material to be heated lies, or the lowest part of a
      melting furnace, into which the melted material settles;
      as, an open-hearth smelting furnace.
      [1913 Webster +PJC]

   Hearth ends (Metal.), fragments of lead ore ejected from
      the furnace by the blast.

   Hearth money, Hearth penny [AS. heor[eth]pening], a tax
      formerly laid in England on hearths, each hearth (in all
      houses paying the church and poor rates) being taxed at
      two shillings; -- called also chimney money, etc.
      [1913 Webster]

            He had been importuned by the common people to
            relieve them from the . . . burden of the hearth
            money.                                --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hearth
    n 1: an open recess in a wall at the base of a chimney where a
         fire can be built; "the fireplace was so large you could
         walk inside it"; "he laid a fire in the hearth and lit it";
         "the hearth was black with the charcoal of many fires"
         [syn: fireplace, hearth, open fireplace]
    2: home symbolized as a part of the fireplace; "driven from
       hearth and home"; "fighting in defense of their firesides"
       [syn: hearth, fireside]
    3: an area near a fireplace (usually paved and extending out
       into a room); "they sat on the hearth and warmed themselves
       before the fire" [syn: hearth, fireside]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "hearth":
   ancestral halls, brood, children, chimney, chimney corner, family,
   family homestead, fender, fire screen, fireboard, fireguard,
   fireplace, fireside, flue, folks, foyer, get, hearth and home,
   hearthstone, hob, home, home place, home roof, home sweet home,
   homefolks, homestead, house, household, hub, ingle, inglenook,
   ingleside, issue, menage, offspring, paternal roof, people, roof,
   rooftree, smokehole, toft



Easton's 1897 Bible Dictionary:

Hearth
   Heb. ah (Jer. 36:22, 23; R.V., "brazier"), meaning a large pot
   like a brazier, a portable furnace in which fire was kept in the
   king's winter apartment.

     Heb. kiyor (Zech. 12:6; R.V., "pan"), a fire-pan.

     Heb. moqed (Ps. 102:3; R.V., "fire-brand"), properly a fagot.

     Heb. yaqud (Isa. 30:14), a burning mass on a hearth.