The relationship among signs and the kinds of things they intend, express, or signify; a concept central to semantics which is the study of how meaning comes about.
Whatever it is that makes what would otherwise be mere sounds and inscriptions into meaningful instruments of communication and understanding.
The philosophical problem is to demystify this power, and to relate it to what we know of ourselves and the world. Contributions to this problem include the theory of speech acts, and the investigation of communication and the relationship between words and ideas, and words and the world.
[Source : Oxford Dictionary of Philosophy]