The Collaborative International Dictionary of English v.0.48:

Bounteous \Boun"te*ous\, a. [OE. bountevous, fr. bounte bounty.]
   Liberal in charity; disposed to give freely; generously
   liberal; munificent; beneficent; free in bestowing gifts; as,
   bounteous production.
   [1913 Webster]

         But O, thou bounteous Giver of all good. --Cowper.
   [1913 Webster] -- Boun"te*ous*ly, adv. --
   Boun"te*ous*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bounteously
    adv 1: in a bountiful manner [syn: bountifully, bounteously,
           plentifully, plenteously]