The Collaborative International Dictionary of English v.0.48:
nonporous \nonporous\ adj. Not porous; especially, not having vessels that appear as pores; as, nonporous wood. Opposite of porous. [WordNet 1.5]WordNet (r) 3.0 (2006):
nonporous adj 1: not porous; especially not having vessels that appear as pores; "nonporous wood" [ant: poriferous, porous]