The Commens Dictionary
Quote from ‘Letters to Paul Carus’
A sign in general is 1st something Real, that is 2nd applicable to an object different from itself and already known to the person to whom it is a sign, and 3rd is capable of interpretation in the mind of that person, so that it will (or would if accepted as veracious sign) have some effect upon him of a kind it was calculated or fit to have.
‘Sign’ (pub. 19.09.14-16:39). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-letters-paul-carus-8.