From WordNet (r) 1.6 [wn]:

  hypertext
       n : machine-readable text that is not sequential but is
           organized so that related items of information are
           connected; "Let me introduce the word hypertext to mean a
           body of written or pictorial material interconnected in
           such a complex way that it could not conveniently be
           presented or represented on paper"--Ted Nelson

From Jay Bolter (1991).Writing space: The computer, hypertext, and the history 
of writing. Hillsdale, New Jersey: Lawrence Erlbaum Associates.

    hypertext
        "...the interactive interconnection of a set of symbolic elements,     
iincluding nontext "writable elements" such as "words, images, sounds, or 
actions that the computer is directed to perform"