The Commens Dictionary
Quote from ‘Letters to Lady Welby’
A sign mediates between the interpretant sign and its object. Taking sign in its broadest sense, its interpretant is not necessarily a sign. [—] A sign […] is an object which is in relation to its object on the one hand and to an interpretant on the other in such a way as to bring the interpretant into a relation to the object corresponding to its own relation to the object. I might say ‘similar to its own’ for a correspondence consists in a similarity; but perhaps correspondence is narrower.