The Collaborative International Dictionary of English v.0.48:

Propinquity \Pro*pin"qui*ty\, n. [L. propinquitas, from
   propinquus near, neighboring, from prope near.]
   [1913 Webster]
   1. Nearness in place; neighborhood; proximity.
      [1913 Webster]

   2. Nearness in time. --Sir T. Browne.
      [1913 Webster]

   3. Nearness of blood; kindred; affinity. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

propinquity
    n 1: the property of being close together [syn: proximity,
         propinquity]