The Latin terms ‘significans’ and ‘significatum’ mean, literally, ‘signifier’ and ‘signified’, resp. A (partly German) list of alternative terms is provided elsewhere. The Latin terms designate concepts that are specific and basic to linguistics as a scientific discipline. They are preferred over more familiar-sounding alternatives because they have none of the conventional connotations of these latter.

Significans and significatum are the two sides of the language sign, given a bilateral concept of the latter. The significans is a perceptible entity, i.e. a configuration of visible, audible etc. components. The significatum is a mental entity, i.e. what the sign contributes to the meaning of the message. The language sign is constituted by these two components and their mutual relation.

The language sign is an element of a language system, this being conceived in the sense of European structural linguistics as founded in Saussure 1916. This entails that it belongs to exactly one language (there are, by definition, no interlingual signs) and that both its significans and its significatum are constituted by principles of its system. This definition relates to what has been called, in European structuralism and specifically by F. de Saussure and L. Hjelmselv, the form of language and excludes the substance of language. That is, it excludes, for the significans, phonetic and graphic aspects, and for the significatum, encyclopedic and pragmatic aspects. These latter become relevant when a language sign is used in a speech act or text. The message (utterance or written representation of it) is then understood as a combination of its significatum with material that is not part of the language system, but part of other aspects of human life and its environment. It is for such reasons that the significans is not simply “the expression”, and the significatum is not simply “the meaning” of a message or of part of it.

Saussure, Ferdinand de 1916, Cours de linguistique générale, publié par Charles Bally et Albert Séchehaye avec la collaboration de Albert Riedlinger. Paris: Payot.