The Collaborative International Dictionary of English v.0.48:

Magnanimously \Mag*nan"i*mous*ly\, adv.
   In a magnanimous manner; with greatness of mind.
   [1913 Webster]

WordNet (r) 3.0 (2006):

magnanimously
    adv 1: in a magnanimous manner; "magnanimously, he forgave all
           those who had harmed him"

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "magnanimously":
   abundantly, acutely, amazingly, amply, astonishingly, awesomely,
   bigheartedly, chivalrously, conspicuously, copiously, eminently,
   emphatically, exceptionally, exquisitely, extraordinarily,
   exuberantly, famously, generously, glaringly, greatheartedly,
   handsomely, impressively, incredibly, intensely, knightly,
   largeheartedly, liberally, magically, magnificently, markedly,
   marvelously, nobly, notably, openhandedly, particularly,
   peculiarly, pointedly, preeminently, profusely, prominently,
   pronouncedly, remarkably, richly, signally, singularly, splendidly,
   strikingly, superlatively, surpassingly, surprisingly, uncommonly,
   unusually, wonderfully, wondrous, worthily