# Index

A sign that means by a real, causal or existential connection to its object.

**Also called:** index sign

**Source:** “whose relation to their objects consists in a correspondence in fact” [Peirce's Theory of Signs (Stanford Encyclopedia of Philosophy)](https://plato.stanford.edu/entries/peirce-semiotics/)

See also: [Icon](/reference/glossary/icon), [Symbol](/reference/glossary/symbol), [Interpretant](/reference/glossary/interpretant).

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Published 2026-10-29. Web page: https://www.mackenziebowes.com/reference/glossary/index-sign