 The modern concept originates in the semiotic theory of Charles Sanders Peirce, in which indexicality is one of the three fundamental sign modalities by which a sign relates to its referent, the others being iconicity and symbolism.Peirce's concept has been adopted and extended by several twentieth-century academic traditions, including those of linguistic pragmatics, linguistic anthropology, and Anglo-American philosophy of language.Words and expressions in language often derive some part of their referential meaning from indexicality.