Where does “కాచు” come from?

కాచు (Telugu) comes from Telugu కాయ, from Proto-Dravidian kāy — fruit.

Ancestry of “కాచు”, step by step

Step	Language	Word	Meaning
1	Telugu	కాయ	unripe fruit; Anything round, as the head
2	Proto-Dravidian	kāy	fruit

కాచు — Etymology, Origin & Word History | Etymology Explorer