What is it called when a word is what it is?

Excuse me, could you please clarify what you mean by "What is it called when a word is what it is?" Are you referring to a linguistic concept where a word's meaning directly corresponds to its referent, or perhaps a philosophical notion of self-referentiality? If it's the former, you might be thinking of the term "denotation," which refers to the literal or direct meaning of a word. If it's the latter, you might be referring to the concept of "autological" words, which describe themselves, such as the word "polysyllabic," which has many syllables just like it describes. Could you please elaborate on your question so I can provide a more accurate answer?