Source : Webster's Revised Unabridged Dictionary (1913)

Porousness \Por"ous*ness\, n.
   1. The quality of being porous.

   2. The open parts; the interstices of anything. [R.]

            They will forcibly get into the porousness of it.
                                                  --Sir K.
                                                  Digby.

Source : WordNet®

porousness
     n : the property of being porous; being able to absorb fluids
         [syn: {porosity}] [ant: {solidity}]