Digital Companion to C. S. Peirce
1903 | Syllabus: Nomenclature and Division of Triadic Relations, as far as they are determined | EP 2:291

A Legisign is a law that is a Sign. This law is usually established by men. Every conventional sign is a legisign. It is not a single object, but a general type which, it has been agreed, shall be significant. Every legisign signifies through an instance of its application, which may be termed a Replica of it. Thus, the word “the” will usually occur from fifteen to twenty-five times on a page. It is in all these occurrences one and the same word, the same legisign. Each single instance of it is a replica. The replica is a sinsign. Thus, every legisign requires sinsigns. But these are not ordinary sinsigns, such as are peculiar occurrences that are regarded as significant. Nor would the replica be significant if it were not for the law which renders it so.

1904 | Letters to Lady Welby | SS 32

As it is in itself, a sign is either of the nature of an appearance, when I call it a qualisign; or secondly, it is an individual object or event, when I call it a sinsign (the syllable sin being the first sillable [sic] of semel, simul, singular, etc); or thirdly, it is of the nature of a general type, when I call it a legisign.

1904 | Firstness, Secondness, Thirdness, and the Reducibility of Fourthness [R] | MS [R] 914:6

…in the first place a sign may, in its own firstness, either be a mere idea or quality of feeling, or it may be a ‘sinsign’, that is, an individual existent (and P. holds, with Hegel, that existence consists in the blind reaction of the existent with the rest of the universe in which it exists), or it may (like a word) be a general type (‘legisign’) to which existents may conform.

1905 [c.] | The Basis of Pragmaticism | MS [R] 284:59

A legisign is a general type which is significant because it may be embodied in instances which have noticeable relations adapting them to be signs of the very objects denoted.