The Collaborative International Dictionary of English v.0.48:

Boundless \Bound"less\, a.
   Without bounds or confines; illimitable; vast; unlimited.
   "The boundless sky." --Bryant. "The boundless ocean."
   --Dryden. "Boundless rapacity." "Boundless prospect of gain."
   --Macaulay.
   [1913 Webster]

   Syn: Unlimited; unconfined; immeasurable; illimitable;
        infinite.
        [1913 Webster] -- Bound"less*ly, adv. --
        Bound"less*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

boundlessly
    adv 1: without bounds; "he is infinitely wealthy" [syn:
           boundlessly, immeasurably, infinitely]