indexical a type of expression whose semantic value is in part determined by features of the context of utterance, and hence may vary with that context. Among indexicals are the personal pronouns, such as ‘I’, ‘you’, ‘he’, ‘she’, and ‘it’; demonstratives, such as ‘this’ and ‘that’; temporal expressions, such as ‘now’, ‘today’, ‘yesterday’; and locative expressions, such as ‘here’, ‘there’, etc. Although classical logic ignored indexicality, many recent practitioners, following Richard Montague, have provided rigorous theories of indexicals in the context of formal semantics. Perhaps the most plausible and thorough treatment of indexicals is by David Kaplan (b.1933; a prominent American philosopher of language and logic whose long-unpublished ‘Demonstratives’ was especially influential; it eventually appeared in J. Almog, J. Perry, and H. Wettstein, eds., Themes from Kaplan, 1988). Kaplan argues persuasively that indexical singular terms are directly referential and a species of rigid designator. He also forcefully brings out a crucial lesson to be learned from indexicals, namely, that there are two types of meaning, which Kaplan calls ‘content’ and ‘character.’ A sentence containing an indexical, such as ‘I am hungry’, can be used to say different things in different contexts, in part because of the different semantic contributions made by ‘I’ in these contexts. Kaplan calls a term’s contribution to what is said in a context the term’s content. Though the content of an indexical like ‘I’ varies with its context, it will nevertheless have a single meaning in the language, which Kaplan calls the indexical’s character. This character may be conceived as a rule of function that assigns different contents to the indexical in different contexts. See also PHILOSOPHY OF LANGUAGE , TOKEN -REFLEX – IV. M.M.