Where does “ondze” come from?

ondze (Old Spanish) comes from Latin undecim, from Latin oinodecem, from Proto-Indo-European óynom déḱm̥t.

Ancestry of “ondze”, step by step

StepLanguageWordMeaning
1Latinundecimeleven; 11
2Latinoinodecem—
3Proto-Indo-Europeanóynom déḱm̥t—
Every word from Proto-Indo-European óynom déḱm̥t →Every word from Latin oinodecem →Every word from Latin undecim →