ostension

Ostension is a communicative act in which the meaning of a term is conveyed by showing or pointing to examples instead of giving a verbal or formal definition. It is central in discussions of ostensive definitions, where the referents of a word are demonstrated directly, often with accompanying language.

In practice, someone might point to a red apple while saying "red" or "apple" to teach a child or clarify which object is being referred to. It relies on shared perceptual context and demonstratives such as "this" or "these" and on the addressee's ability to infer which category is being illustrated. Ostension can also function in nonverbal communication, for instance by pointing to a scene to convey which event is meant.

Ostension highlights the social and pragmatic aspects of meaning, showing that language partly depends on demonstrative acts and joint attention. However, it does not by itself provide a complete account of a term's extension or the necessary and sufficient conditions for counting as an instance of the category; many terms require more explicit stipulation or rule-based definitions, and ambiguous or vague terms may be difficult to illustrate unambiguously.

In cognitive science and language acquisition, ostension is seen as foundational for early word learning, where caregivers' pointing and naming help infants map words to concepts. In linguistics and philosophy, discussions of ostension intersect with theories of indexicality, demonstration, and the pragmatics of communication.

See also: ostensive definition, teaching by demonstration, indexicality, demonstratives, joint attention.