The Collaborative International Dictionary of English v.0.48:

Cancellous \Can"cel*lous\, a. [Cf. L. cancellosus covered with
   bars.] (Anat.)
   Having a spongy or porous structure; made up of cancelli;
   cancellated; as, the cancellous texture of parts of many
   bones.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cancellous
    adj 1: having an open or latticed or porous structure [syn:
           cancellate, cancellated, cancellous]