Entry record from Schapper (2020): Wersing Peitoko
-kaku[-ˈkaku]
• n. younger sibling (male or female)(eng).adik (lakilaki atau perempuan)(ind).
ekakuyour younger sibling(eng), adik engkau(ind)
nekaku lmimy younger brother(eng), adik laki-laki saya(ind)
nekaku meimy younger sister(eng), adik perempuan saya(ind)
See also: -nang
Source: Hans Retebana