Bibliography

Foundations of Mathematics [R]

A sign in some sense corresponds to an object and also determines an interpretant sign, or is capable of doing so. Although it is not necessary that any person should originate the sign or that any person should interpret it, yet it will contribute to perspicuity to use language as if such were the case, and to speak of the utterer and the interpreter.

If a sign refers to an object well known already to utterer and interpreter, and gives neither party any latitude as to what it represents, it may be called a singular sign, or singular.

If a sign allows the utterer a certain latitude of choice as to what his meaning may be; so that he may perhaps defend its applicability in several ways […] then the sign may be said to be vague, or non-definite.