Where does “pastu” come from?

pastu (Malay) comes from Malay tu, from Malay itu, from Proto-Malayic (i)tu(ʔ), from Proto-Malayo-Polynesian (i-)tu, from Proto-Austronesian (i-)Cu — that.

Ancestry of “pastu”, step by step

StepLanguageWordMeaning
1Malaytuthat
2Malayituthat; it
3Proto-Malayic(i)tu(ʔ)that
4Proto-Malayo-Polynesian(i-)tuthat
5Proto-Austronesian(i-)Cuthat
Every word from Proto-Austronesian (i-)Cu →Every word from Proto-Malayo-Polynesian (i-)tu →Every word from Proto-Malayic (i)tu(ʔ) →