The Collaborative International Dictionary of English v.0.48:
Solidly \Sol"id*ly\, adv. In a solid manner; densely; compactly; firmly; truly. [1913 Webster]WordNet (r) 3.0 (2006):
solidly adv 1: as an undiversified whole; "the unions voted solidly for Roosevelt" 2: with strength and soundness; "a solidly built house"