Subindex, Hyposeme
(cf. Index; see also Hypoicon)

"Subindices or hyposemes are signs which are rendered such principally by an actual connection with their objects. Thus a proper name, [a] personal demonstrative, or relative pronoun or the letter attached to a diagram, denotes what it does owing to a real connection with its object but none of these is an Index, since it is not an individual." ('A Syllabus of Certain Topics of Logic', EP 2:274, 1903)

The concept in question (or a related form) is highlighted with a brown font.
Selected definition-like characterizations are highlighted with a light grey background.
Quotes are presented in reverse chronological order.

Abbreviations (CP, EP, etc.) and sources; see here