The Collaborative International Dictionary of English v.0.48:

comprehendible \comprehendible\ adj.
   able to be understood. Opposite of incomprehensible.

   Note: [Narrower terms: clear, distinct] Also See: clear,
         explicable, fathomable, intelligible.

   Syn: comprehensible.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

comprehendible
    adj 1: capable of being comprehended or understood; "an idea
           comprehensible to the average mind" [syn:
           comprehensible, comprehendible] [ant:
           incomprehensible, uncomprehensible]