1. adj. (semiotics) A mode of relationship in a sign between a sign vehicle and its referent in which the former is perceived as resembling or imitating the latter (recognizably looking, sounding, feeling, tasting, or smelling like it)—being similar in possessing some of its qualities (e.g. a portrait, a diagram, onomatopoeia, metaphor, ‘realistic’ sounds in music, sound effects in radio drama). Note that in semiotics, iconicity is not confined to visual resemblance. The iconic mode, the indexical mode, and the symbolic mode are concepts in the Peircean model of the sign, where they represent relationships between the representamen and the object. Where the relation is solely iconic, the sign may be referred to as an icon; however, most signs involve more than one mode. Photographs are sometimes misleadingly labelled as iconic in the semiotic sense. Although this may be legitimate where what is being stressed is the use of photographic conventions, the primary characteristic of the medium is that it is indexical, since it is hardly an accident that photographs ‘resemble’ what they depict.
2. In popular usage, anything expected to be instantly recognized as famous (a popular icon) by any fully-fledged member of a particular culture or subculture. Any famous visual image can thus be iconic (see also conversational currency). In this non-semiotic sense, an iconic photograph is one which is famous in its own right, especially if it is a memorable depiction of a famous person or event. Note that events themselves are not iconic: only famous representations of them. However, major celebrities or stars (not just famous representations of them) are often described as (cultural) icons, where there is an added connotation of widespread admiration.
3. (signage) Relating to pictorial signs signifying familiar concepts (not necessarily based on resemblance). In this sense, iconic communication is the informational use of simple pictorial signs or ‘icons’, notably in computing environments and public signage and usually in coordinated sets, as a kind of visual shorthand for certain basic functions or standardized messages. For instance, a simplified outline of a house on a webpage button is widely used to indicate that clicking on it will take the user to the website homepage.
4. Each of the above senses can be seen as deriving from different aspects of the ancient idea of religious icons: works of visual art representing sacred figures which may be venerated as holy images by devout believers.