Where does “caos” come from?

caos (Middle Dutch) comes from Latin Chaos, from Ancient Greek χάος, from Proto-Indo-European ǵʰeh₂- — to yawn; to gape; yawn.

Ancestry of “caos”, step by step

Step	Language	Word	Meaning
1	Latin	Chaos	the shapeless primordial universe
2	Ancient Greek	χάος	the primordial state of existence; space, air;...
3	Proto-Indo-European	ǵʰeh₂-	to yawn; to gape; yawn