Wordnet 3.0
NOUN (1)
1. 
 a type of fiberboard; 
The Collaborative International Dictionary of English v.0.48:
Masonite \Masonite\ prop. n. [trademark.]
   A type of fiberboard. [trademark]
   [WordNet 1.5]
WordNet (r) 3.0 (2006):
Masonite
    n 1: a type of fiberboard