Where does “արգելք” come from?

արգելք (Old Armenian) comes from Old Armenian արգել, from Proto-Indo-European h₂erk- — to protect, guard, hold, lock.

Ancestry of “արգելք”, step by step

Step	Language	Word	Meaning
1	Old Armenian	արգել	hinderance, obstacle, opposition, impediment,...
2	Proto-Indo-European	h₂erk-	to protect, guard, hold, lock

արգելք — Etymology, Origin & Word History | Etymology Explorer