Thus, if a sunflower, in turning towards the sun, becomes by that very act fully capable, without further condition, of reproducing a sunflower which turns in precisely corresponding ways toward the sun, and of doing so with the same reproductive power, the sunflower would become a Representamen of the sun.
— C.S. Peirce, Collected Papers, CP 2.274
In his picturesque illustration of a sign relation, along with his tracing of a corresponding sign process, or semiosis, Peirce uses the technical term representamen for his concept of a sign, but the shorter word is precise enough, so long as one recognizes its meaning in a particular theory of signs is given by a specific definition of what it means to be a sign.
Resources
cc: Cybernetics • Ontolog • Peirce List (1) (2) • Structural Modeling • Systems Science
The abstract consideration of how 
and 
use this set of signs leads to the contemplation of a pair of triadic relations, the sign relations 
and 
reflecting the differential use of these signs by 
respectively.
consists of eight triples of the form 
where the object 
belongs to the object domain 
the sign 
belongs to the sign domain 
the interpretant sign 
belongs to the interpretant domain 
and where it happens in this case that 
The union 
is often referred to as the syntactic domain, but in this case 
![\begin{array}{ccc} L_\mathrm{A}, L_\mathrm{B} & \subseteq & O \times S \times I \\[8pt] O & = & \{ \mathrm{A}, \mathrm{B} \} \\[8pt] S & = & \{ \, {}^{\backprime\backprime} \mathrm{A} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{B} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{i} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{u} {}^{\prime\prime} \, \} \\[8pt] I & = & \{ \, {}^{\backprime\backprime} \mathrm{A} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{B} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{i} {}^{\prime\prime}, \, {}^{\backprime\backprime} \mathrm{u} {}^{\prime\prime} \, \} \end{array}](https://s0.wp.com/latex.php?latex=%5Cbegin%7Barray%7D%7Bccc%7D++L_%5Cmathrm%7BA%7D%2C+L_%5Cmathrm%7BB%7D+%26+%5Csubseteq+%26+O+%5Ctimes+S+%5Ctimes+I++%5C%5C%5B8pt%5D++O+%26+%3D+%26+%5C%7B+%5Cmathrm%7BA%7D%2C+%5Cmathrm%7BB%7D+%5C%7D++%5C%5C%5B8pt%5D++S+%26+%3D+%26+%5C%7B+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7BA%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7BB%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7Bi%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7Bu%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D+%5C%2C+%5C%7D++%5C%5C%5B8pt%5D++I+%26+%3D+%26+%5C%7B+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7BA%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7BB%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7Bi%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D%2C+%5C%2C+%7B%7D%5E%7B%5Cbackprime%5Cbackprime%7D+%5Cmathrm%7Bu%7D+%7B%7D%5E%7B%5Cprime%5Cprime%7D+%5C%2C+%5C%7D++%5Cend%7Barray%7D&bg=ffffff&fg=000000&s=0&c=20201002)
in 
to mean the same thing 
to mean, namely, 
in 
to mean, namely, 
and 
each of which is a subset of the same cartesian product 
The structures of 
can be described in the following way.
is isomorphic to the 
so 
or the boolean cube 
is equivalent to addition modulo 2, where 
acts in the usual manner but 
In its logical interpretation, the plus sign can be used to indicate either the boolean operation of 
” (CP 2.318, unfortunately there is a hole in my PDF of CP right after and I [left] my paper edition at the library of my university, inaccessible at the moment).
Inquiry Into Inquiry 