Source : Webster's Revised Unabridged Dictionary (1913)

Baa \Baa\ (b[aum]), v. i. [Cf. G. b["a]en; an imitative word.]
   To cry baa, or bleat as a sheep.

         He treble baas for help, but none can get. --Sir P.
                                                  Sidney.

Baa \Baa\ (b[aum]), n.; pl. {Baas} (b[aum]z). [Cf. G. b["a].]
   The cry or bleating of a sheep; a bleat.

Source : WordNet®

baa
     n : the cry made by sheep

baa
     v : cry plaintively; "The lambs were bleating" [syn: {bleat}, {blate},
          {blat}]