1. An adjective is autological if and only if it describes itself. For example “short” is autological, since the word “short” is short. “English,” “unhyphenated” and “pentasyllabic” are also autological.
  
2. An adjective is heterological if it does not describe itself. Hence “long” is a heterological word, as are “abbreviated” and “monosyllabic.”

  
Is “autological” autological?

It can be chosen consistently to be either:

    * if we say that “autological” is autological, and then ask if it applies to itself, then yes, it does, and thus is autological;
    * if we say that “autological” is not autological, and then ask if it applies to itself, then no, it does not, and thus is not autological.

This is the opposite of the situation for heterological: while “heterological” logically cannot be autological or heterological, “autological” can be either.

In logical terms, the situation for “autological” is:

    “autological” is autological if and only if “autological” is autological
    A if and only if A, a tautology

while the situation for “heterological” is:

    “heterological” is heterological if and only if “heterological” is autological
    A if and only if not A, a contradiction.

— Wikipedia on Grelling–Nelson paradox

2011.02.24 Thursday ACHK