indexical

hakemistollinen Of, pertaining to, or like, an index; having the form of an index.
puhekieltä Having the character of pointing to, or indicate indicating, a particular state of affairs
2012, Michael Silverstein, ‘The walked down the street’, London Review of Books, vol. 34 no. 21:

In order that they might represent the worlds of experience and imagination, such symbols have to be put together with ‘indexical’ signs, as Peirce termed them, such as articles (the, some), demonstratives (this, those), tense-inflections (walk-s, walk-ed), moods (may/might walk, shall/should walk) etc.