Search Result for "antrum": 
Wordnet 3.0

NOUN (1)

1. a natural cavity or hollow in a bone; 



The Collaborative International Dictionary of English v.0.48:

Antrum \An"trum\, n.; pl. Antra. [L., fr. Gr. ?.]
   A cavern or cavity, esp. an anatomical cavity or sinus.
   --Huxley.
   [1913 Webster]


WordNet (r) 3.0 (2006):

antrum
    n 1: a natural cavity or hollow in a bone