(1):

(n.) 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.

(2):

(n.) The house itself, as the abode of comfort to its inmates and of hospitality to strangers; fireside.

(3):

(n.) 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.