Where does “ցածր” come from?

ցածր (Armenian) comes from Old Armenian ցած, from Proto-Indo-European ḱadyo-, from Proto-Indo-European ḱad- — to fall.

ցածր (Armenian): low

Definitions

Step	Language	Word	Meaning
1	Old Armenian	ցած	low, lower; humble, lowly, modest, moderate,...
2	Proto-Indo-European	ḱadyo-	—
3	Proto-Indo-European	ḱad-	to fall

ցածր — Etymology, Origin & Word History | Etymology Explorer