A relational adjective*. Pertainyms are adjectives that classify a noun. Examples are 'cherry tree', 'musical instrument', and ' industrial complex'. I have found some sources that claim that pertainyms don’t have antonyms, which would imply the 'fake'/'real' and 'dead'/'live' cannot be pertainyms. (Another source claims that 'slowly' is a pertainym; slowly does have an antonym in quickly).
Informally, pertainym can be used to mean 'relating or pertaining to'.
* AKA classifying adjective, although relational adjective is the more common term.