Source : Webster's Revised Unabridged Dictionary (1913)

Brood \Brood\, a.
   1. Sitting or inclined to sit on eggs.

   2. Kept for breeding from; as, a brood mare; brood stock;
      having young; as, a brood sow.

Brood \Brood\ (br[=o]ch), v. i. [imp. & p. p. {Brooded}; p. pr.
   & vb. n. {Brooding}.]
   1. To sit on and cover eggs, as a fowl, for the purpose of
      warming them and hatching the young; or to sit over and
      cover young, as a hen her chickens, in order to warm and
      protect them; hence, to sit quietly, as if brooding.

            Birds of calm sir brooding on the charmed wave.
                                                  --Milton.

   2. To have the mind dwell continuously or moodily on a
      subject; to think long and anxiously; to be in a state of
      gloomy, serious thought; -- usually followed by over or
      on; as, to brood over misfortunes.

            Brooding on unprofitable gold.        --Dryden.

            Brooding over all these matters, the mother felt
            like one who has evoked a spirit.     --Hawthorne.

            When with downcast eyes we muse and brood.
                                                  --Tennyson.

Brood \Brood\ (br[=oo]d), n. [OE. brod, AS. br[=o]d; akin to D.
   broed, OHG. bruot, G. brut, and also to G. br["u]he broth,
   MHG. br["u]eje, and perh. to E. brawn, breath. Cf. {Breed},
   v. t.]
   1. The young birds hatched at one time; a hatch; as, a brood
      of chickens.

            As a hen doth gather her brood under her wings.
                                                  --Luke xiii.
                                                  34.

            A hen followed by a brood of ducks.   --Spectator.

   2. The young from the same dam, whether produced at the same
      time or not; young children of the same mother, especially
      if nearly of the same age; offspring; progeny; as, a woman
      with a brood of children.

            The lion roars and gluts his tawny brood.
                                                  --Wordsworth.

   3. That which is bred or produced; breed; species.

            Flocks of the airy brood, (Cranes, geese or
            long-necked swans).                   --Chapman.

   4. (Mining) Heavy waste in tin and copper ores.

   {To sit on brood}, to ponder. [Poetic] --Shak.

Brood \Brood\ (br[=oo]d), v. t.
   1. To sit over, cover, and cherish; as, a hen broods her
      chickens.

   2. To cherish with care. [R.]

   3. To think anxiously or moodily upon.

            You'll sit and brood your sorrows on a throne.
                                                  --Dryden.

Source : WordNet®

brood
     n : the young of an animal cared for at one time
     v 1: think moodily or anxiously about something [syn: {dwell}]
     2: hang over, as of something threatening, dark, or menacing;
        "The terrible vision brooded over her all day long" [syn:
        {hover}, {loom}, {bulk large}]
     3: be in a huff and display one's displeasure; "She is pouting
        because she didn't get what she wanted" [syn: {sulk}, {pout}]
     4: be in a huff; be silent or sullen [syn: {grizzle}, {stew}]
     5: sit on (eggs); "Birds brood"; "The female covers the eggs"
        [syn: {hatch}, {cover}, {incubate}]