Source : Webster's Revised Unabridged Dictionary (1913)

Patency \Pa"ten*cy\, n. [See {Patent}.]
   1. The condition of being open, enlarged, or spread.

   2. The state of being patent or evident.

Source : WordNet®

patency
     n 1: the openness (lack of obstruction) of a bodily passage or
          duct
     2: the property of being easy to see and understand [syn: {obviousness},
         {noticeability}, {noticeableness}]