The Collaborative International Dictionary of English v.0.48:

deixis \deixis\ (d[imac]k"s[i^]s), n. (Grammar)
   the function or operation of a deictic word; the function of
   pointing or specifying from the perspective of a participant
   in an act of speech or writing; aspects of a communication
   whose interpretation depends on knowledge of the context in
   which the communication occurs.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

deixis
    n 1: the function of pointing or specifying from the perspective
         of a participant in an act of speech or writing; aspects of
         a communication whose interpretation depends on knowledge
         of the context in which the communication occurs