Where does “[[břuch]], [[břucho]]” come from?

[[břuch]], [[břucho]] (Old Czech) comes from Proto-Slavic břȗxo — belly.

Ancestry of “[[břuch]], [[břucho]]”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	břȗxo	belly

[[břuch]], [[břucho]] — Etymology, Origin & Word History | Etymology Explorer