The Collaborative International Dictionary of English v.0.48:
Principally \Prin"ci*pal*ly\, adv. In a principal manner; primarily; above all; chiefly; mainly. [1913 Webster]WordNet (r) 3.0 (2006):
principally adv 1: for the most part; "he is mainly interested in butterflies" [syn: chiefly, principally, primarily, mainly, in the main]