The Collaborative International Dictionary of English v.0.48:

Proximity \Prox*im"i*ty\, n. [L. proximitas: cf. F. proximit['e]
   See Proximate, and cf. Propinquity, Approach.]
   The quality or state of being next in time, place, causation,
   influence, etc.; immediate nearness, either in place, blood,
   or alliance.
   [1913 Webster]

         If he plead proximity of blood
         That empty title is with ease withstood. --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

proximity
    n 1: the property of being close together [syn: proximity,
         propinquity]
    2: the region close around a person or thing
    3: a Gestalt principle of organization holding that (other
       things being equal) objects or events that are near to one
       another (in space or time) are perceived as belonging
       together as a unit [syn: proximity, law of proximity]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "proximity":
   accord, addition, adjacency, adjunct, affairs, affiliation,
   affinity, alliance, approach, approximation, assemblage,
   association, bond, closeness, combination, confines, connectedness,
   connection, contiguity, contiguousness, contrariety, convergence,
   dealings, deduction, disjunction, environs, filiation, foreground,
   homology, immediacy, immediate foreground, intercourse, intimacy,
   junction, juxtaposition, liaison, link, linkage, linking,
   mutual attraction, nearness, neighborhood, nighness, precinct,
   propinquity, purlieus, rapport, relatedness, relation, relations,
   relationship, similarity, sympathy, tie, tie-in, togetherness,
   union, vicinage, vicinity



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PROXIMITY. Kindred between two persons. Dig. 38, 16, 8.