1. n. an objective, observable indication of a disorder or disease. See also soft sign.

2. n. in linguistics and semiotics, anything that conveys meaning; a sign may be either verbal (e.g., a spoken or written word) or nonverbal (e.g., a hairstyle). The term is now mainly associated with approaches deriving from the theory of Swiss linguist Ferdinand de Saussure (1857–1913), who emphasized the arbitrary nature of linguistic signs (i.e., the lack of any necessary relationship between the material signifier and the idea signified). The application of this idea to nonlinguistic sign systems provided the basic method of structuralism in the social sciences.

3. vb. to communicate using sign language.