The Collaborative International Dictionary of English v.0.48:

Divisibility \Di*vis`i*bil"i*ty\, n. [Cf. F. divisibilit['e].]
   The quality of being divisible; the property of bodies by
   which their parts are capable of separation.
   [1913 Webster]

         Divisibility . . . is a primary attribute of matter.
                                                  --Sir W.
                                                  Hamilton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

divisibility
    n 1: the quality of being divisible; the capacity to be divided
         into parts or divided among a number of persons