| Definition -
A behavior or utterance that points directly at the referent. For example:
(1) The word me points directly at whoever is speaking, and
(2) the word now refers to the time at which the word now is said.
1. As opposed to a symbolic sign, which can stand in place of its referent and an iconic sign, which resembles what it refers to.
Etymology - The word derives from the Latin index, forefinger, pointer, sign, or list. I believe that semiotic sense of the term was coined by the philosopher Charles Sanders Peirce when he developed his sign modalities, but I still haven't confirmed this. If anyone knows a good confirming reference, please point me to it.