Definition by Charles Sanders Peirce (1932):

A sign, or representamen, is something which stands to somebody for something in some respect or capacity…. every representamen being thus connected with three things, the ground, the object, and the interpretant (2:228)…. The Sign can only represent the Object and tell about it. It cannot furnish acquaintance with or recognition of that Object; for that is what is meant in this volume by the Object of a Sign; namely, that with which it presupposes an acquaintance in order to convey some further information concerning it (2:231, italics added).

Peirce broadly classified sign-object relationships as:

Noteworthy is Peirce’s comment that the sign “cannot furnish acquaintance with or recognition of that Object.”  For ‘right opinion’, direct apprehension of the object is an important condition with respect to clarity of meaning of signs used in communication.  Otherwise, people do not really know what they are talking about if they lack acquaintance or recognition—two kinds of ‘knowing that one’.  See Maccia (1987), Genetic Epistemology of Intelligent Natural Systems.

For an authoritative resource see:

  • Short, T. L. (2007).  Peirce’s theory of signs.  New York, NY:  Cambridge University Press.