I think we need to reflect upon the circumstance that every word implies some proposition or, what is the same thing, every word, concept, symbol has an equivalent term — or one which has become identified with it, — in short, has an interpretant.

Consider, what a word or symbol is;  it is a sort of representation.  Now a representation is something which stands for something.  I will not undertake to analyze, this evening, this conception of standing for something — but, it is sufficiently plain that it involves the standing to something for something.  A thing cannot stand for something without standing to something for that something.  Now, what is this that a word stands to?  Is it a person?

We usually say that the word homme stands to a Frenchman for man.  It would be a little more precise to say that it stands to the Frenchman’s mind — to his memory.  It is still more accurate to say that it addresses a particular remembrance or image in that memory.  And what image, what remembrance?  Plainly, the one which is the mental equivalent of the word homme — in short, its interpretant.  Whatever a word addresses then or stands to, is its interpretant or identified symbol.  […]

The interpretant of a term, then, and that which it stands to are identical.  Hence, since it is of the very essence of a symbol that it should stand to something, every symbol — every word and every conception — must have an interpretant — or what is the same thing, must have information or implication.  (Peirce 1866, Chronological Edition 1, pp. 466–467).