Grelling–Nelson paradox

The Grelling–Nelson paradox highlights a problem in language and classification. It involves the term "heterological," which refers to adjectives that do not describe themselves. For example, "long" is heterological because it does not describe the word "long." The paradox arises when we ask if "heterological" itself is heterological. If "heterological" describes itself, it becomes "autological" (self-describing); if it doesn't describe itself, then it is heterological. This contradiction raises questions about self-reference and how we classify concepts, revealing limitations in our understanding of language and definitions.