"In Foundations of the Theory of Signs , the three terms in question were defined follows: pragmatics as the study of "the relation of signs to interpreters", semantics as the study of "the relations of signs to the objects to which the signs are applicable", syntactics as the study of "the formal relations of signs to one another."

“Men are the dominant sign-using animals. Animals other than man do, of course, respond to certain things as signs of something else, but such signs do not attain the complexity and elaboration which is found in human speech, writing, art, testing devices, medical diagnosis, and signaling instruments. Science and signs are inseparably interconnected, since science both presents men with more reliable signs and embodies its results is systems of signs. Human civilization is dependent upon signs and systems of signs, and the human mind is inseparable from the functioning of signs - if indeed mentality is not to be identified with such functioning.”

“The full characterization of a language may now be given: A language in the full semiotic sense of the term is any intersubjective set of sign vehicles whose usage is determined by syntactical, semantical, and pragmatical rules.”

“What of the term 'meaning'? In the preceding discussion the term 'meaning' has been deliberately avoided. In general it is well to avoid this term in discussions of signs; theoretically, it can be dispensed with entirely and should not be incorporated into the language of semiotic. But since the term has had such a notorious history, and since in its consideration certain important implications of the present account can be made clear, the present section is devoted to its discussion.”

“The term "meaning" is not here included among the basic terms of semiotic. This term, useful enough at the level of everyday analysis, does not have the precision necessary for scientific analysis. Accounts of meaning usually throw a handful of putty at the target of sign phenomena, while a technical semiotic must provide us with words which are sharpened arrows. "Meaning" signifies any and all phases of sign-processes , and frequently suggests mental and valuational processes as well; hence it is desirable for semiotic to dispense with the term and to introduce special terms for the various factors which meaning fails to discriminate.”

“Empirical problems of a nonlinguistic sort are not solved by linguistic considerations, but it is important that the two kinds of problems not be confused and that nonlinguistic problems be expressed in such a form as aids their empirical solution.”

“The process in which something functions as a sign may be called . This process, in a tradition which goes back to the Greeks, has commonly been regarded as involving three factors: that which acts as a sign, that which the sign refers to, and the effect on some interpreter in virtue of which the thing in question is a sign to that interpreter. These three components in semiosis may be called, respectively, the sign vehicle, the designatum, and the interpretant; the interpreter may be included as a fourth factor. These terms make explicit the factors left undesignated in the common statement that a sign refers to something for someone.”