Sinsign is a term used by Charles S. Peirce to denote a particular type of sign, in which the individual event or object serves as a sign vehicle.
If a knock on the door announces incoming guests, that knock is a sinsign. More precisely, it is a Dicent Indexical Sinsign
It is a Dicent (dicisign), as it represents an effect conveyed through the function of a proposition (“Guests have arrived”). It is indexical because there is an actual physical connection between the sign vehicle and its object (the sound of a knock and the guests declaring their arrival by that knock).
Finally, it is a sinsign, insofar as the knocks appearing here and now – the sounds in their singularity – serve as a sign vehicle.
The signs can be considered on their own, ie. in terms of what the sign vehicle itself is, insofar as different things play the role of signs.
When this role is played by one quality, we have (according to the use of Charles Peirce) a qualisign; when something general or similar to a rule performs this function, we have a legisign; and when something actual or individually existing takes on the role of a sign, we have a sinsign.
The trichotomy qualitative sign, singular sign, and sign is usually part of a complex classification of signs created by Peirce, insofar as he also considers the sign in its relation to the object and the interpreter. Each such examination gives rise to a trichotomy.
To a dynamic object, the sign can be iconic, index, or symbol.
It can be a rheme, a dicisign, or an argument to its interpreter.
Peirce doesn’t stop there. He goes on to explore the possibilities of combining the specific types of signs, or more precisely the sign functions, identified in these three trichotomies.
