The Collaborative International Dictionary of English v.0.48:

Lavishly \Lav"ish*ly\, adv.
   In a lavish manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lavishly
    adv 1: in a wasteful manner; "the United States, up to the
           1920s, used fuel lavishly, mainly because it was so
           cheap" [syn: extravagantly, lavishly]
    2: in a rich and lavish manner; "lavishly decorated" [syn:
       lavishly, richly, extravagantly]

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "lavishly":
   abundantly, affluently, aplenty, beyond measure, bigheartedly,
   bottomlessly, bounteously, bountifully, copiously, diffusely,
   effusely, extravagantly, exuberantly, freehandedly, freeheartedly,
   freely, fully, generously, graciously, greatheartedly, handsomely,
   hospitably, in abundance, in full measure, in good supply,
   in plenty, in quantity, inexhaustibly, largeheartedly, liberally,
   maximally, more than enough, no end, openhandedly, openheartedly,
   opulently, out of measure, overabundantly, overflowingly,
   plenteously, plentifully, prodigally, profusely, richly, riotously,
   superabundantly, to the full, ungrudgingly, unselfishly,
   unsparingly, unstintingly, with both hands, with open hands,
   without measure, without stint