Indonesian wulan

← Indonesian bulan (doublet)

← Javanese wulan (borrowed)

← Old Javanese wulan (derived)

← Proto-Austronesian *bulaN (derived)

← Proto-Malayo-Polynesian *bulan (derived)

→ Indonesian bulan (doublet)

→ Indonesian triwulan (prefix)

→ Indonesian caturwulan (affix)