Where does “це́зий” come from?

це́зий (Russian) comes from Latin caesius, from Latin caedō, from Proto-Italic kaidō, from Proto-Indo-European keh₂id-.

Ancestry of “це́зий”, step by step

Step	Language	Word	Meaning
1	Latin	caesius	bluish-gray, gray-eyed, blue-eyed, cat-eyed;...
2	Latin	caedō	—
3	Proto-Italic	kaidō	to cut, to hew, to fell
4	Proto-Indo-European	keh₂id-	—

це́зий — Etymology, Origin & Word History | Etymology Explorer