The sign, the signifier, and the signified are concepts of the school of thought known as structuralism, founded by Ferdinand de Saussure, a Swiss linguist, during lectures he gave between 1907 and 1911 at the University of Geneva. His views revolutionized the study of language and inaugurated modern linguistics. The theory also profoundly influenced other disciplines, especially anthropology, sociology, and literary criticism. The central tenet of structuralism is that the phenomena of human life, whether language or media, are not intelligible except through their network of relationships, making the sign and the system (or structure) in which the sign is embedded primary concepts. As such, a sign -- for instance, a word -- gets its meaning only in relation to or in contrast with other signs in a system of signs.

At least two other terms are used for signifier and signified:

Saussure choose the term "sign" over "symbol" because the latter implies motivation. For Saussure, the sign is arbitrary. Virtually all signs, Saussure maintains, have only arbitrarily ascribed meanings. Since Saussure, this notion has been taken as axiomatic in Western linguistics and philosophy. 

A common mistake is to construe the signifier and the sign as the same thing. In my view, another common mistake, perhaps related to the first, is to speak of a signifier without a signified or a sign, or to speak of a signified without a signifer or a sign. Used in reference to Saussure's original formulations, both locutions are nonsensical. In language, a lone signifier would be an utterly meaningless sound or concatenation of sounds. But it is even more absurd to speak of a signified without signifier or sign: It would, I believe, have to be a sort of half thought, something never thought before, a thought that exists solely outside the domain of language, a fleeting, private, chaotic thought that makes no sense even to the thinker -- an unthought. Another mistake is to endow a sign with meaning outside the presence of other signs. Except as part of the whole system, signs do not and cannot exist.

Saussure provides an explicit basis for the expansion of his science of signs beyond linguistics: "It is possible," he says, "to conceive of a science which studies the role of signs as part of social life. ... We shall call it semiology. It would investigate the nature of signs and the laws governing them. Since it does not yet exist, one cannot say for certain that it will exist. But it has a right to exist, a place ready for it in advance."

Regardless of how linguistic signs (and perhaps other signs, too) are analyzed, meaning may in fact be unrecoverable, both to the analyst and to the participants in an exchange of signs. It is my belief that meaning is indeed ultimately indeterminate, a position that bodes well with what very well be a fact of language. With respect to indeterminacy, some linguists, postmodern theorists, and analytic philosophers seem to be in agreement. Brown and Yule, both of whom are linguists, write that "the perception and interpretation of each text is essentially subjective."

Philosophy of Language Questions and Answers