deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
A commentarist of /pANini is whoever wrote a "commentary" (bhASyam भाष्यम्) on it, that is, an explanation of how the /pANinIya works, organized sUtra by sUtra.
Such as YT :)
Instead of commentarist, you may say "scholiast" if you want to sound highfalutin', or "footnotemaker" if you want to get understood quick.
Writing commentaries is an old Indian tradition. Some authors first write a short version of their work that can be memorized easily, but is so compact that it is useless without explanations. Then they write a commentary on it themselves. No one gets to understand the /pANinIya, or the yogasUtra योगसूत्र, or the brahmasUtra ब्रह्मसूत्र, without heaps of explaining.
Sometimes, as centuries pass by, students become duller and duller and eventually they are unable to understand the commentary as well. Then someone writes a commentary on the commentary.
A commentary on a commentary is called a **TIkA- टीकाॱ. Which is a very useful word for grammar examples — words that start with T ट् are rare.
A good example of TIkA टीका is candravasu 's translation of the /aSTAdhyAyI. He took the /kAzikA and explained parts of it in English.