1. (semiotics) A meaningful unit which is interpreted as ‘standing for’ something other than itself. Signs are found in the physical form of words, images, sounds, acts, or objects (this physical form is sometimes known as the sign vehicle). Signs have no intrinsic meaning and become signs only when sign-users invest them with meaning with reference to a recognized code. The two main models of the sign are the Saussurean model and the Peircean model: see also conventional sign; natural sign.
2. An advertisement located in a public space.