The Collaborative International Dictionary of English v.0.48:

Deictic \Deic"tic\ (d[imac]k"t[i^]k), a. [Gr. deiktiko`s serving
   to show or point out, fr. deikny`nai to show.]
   1. (Logic) Direct; proving directly; -- applied to reasoning,
      and opposed to elenchtic or refutative.
      [1913 Webster]

   2. (Grammar) showing or pointing to directly; pertaining to
      deixis; -- used to designate words that specify identity,
      location, or time from the perspective of one of the
      participants in a discourse, using the surrounding context
      as reference; as, the words this, that, these, those,
      here, there, now, then, we, you, they, the former, and the
      latter serve a deictic function.
      [PJC]

WordNet (r) 3.0 (2006):

deictic
    adj 1: relating to or characteristic of a word whose reference
           depends on the circumstances of its use; "deictic
           pronouns"
    n 1: a word specifying identity or spatial or temporal location
         from the perspective of a speaker or hearer in the context
         in which the communication occurs; "words that introduce
         particulars of the speaker's and hearer's shared cognitive
         field into the message"- R.Rommetveit [syn: deictic,
         deictic word]