Where does “coiso” come from?

coiso (Portuguese) comes from Portuguese coisa, from Old Portuguese cousa, from Latin causa, from Old Latin caussa, from Proto-Indo-European kawd-teh₂.

Ancestry of “coiso”, step by step

Step	Language	Word	Meaning
1	Portuguese	coisa	thing; thingamajig; gizmo, thingy
2	Old Portuguese	cousa	thing
3	Latin	causa	cause, reason; case, claim, contention; motive,...
4	Old Latin	caussa	cause, reason, purpose; case, claim; Archaic form...
5	Proto-Indo-European	kawd-teh₂	—

Every word from Proto-Indo-European kawd-teh₂ →Every word from Old Latin caussa →Every word from Latin causa →