Where does “Hán Nôm” come from?

Hán Nôm (Vietnamese) comes from Vietnamese Nôm, from Old Portuguese non, from Latin nōn, from Old Latin noenum, from Proto-Indo-European óynos — one; single.

Hán Nôm (Vietnamese): chữ Hán literary Chinese characters and chữ Nôm characters for vernacular Vietnamese, as a whole

Definitions

chữ Hán literary Chinese characters and chữ Nôm characters for vernacular Vietnamese, as a whole

Ancestry of “Hán Nôm”, step by step

Hán Nôm traces back through two separate lines of ancestry.

via Vietnamese Nôm

Step	Language	Word	Meaning
1	Vietnamese	Nôm	written in Vietnamese using chữ Nôm
2	Old Portuguese	non	no, not
3	Latin	nōn	not
4	Old Latin	noenum	—
5	Proto-Indo-European	óynos	one; single

via Vietnamese hạn

Step	Language	Word	Meaning
1	Vietnamese	hạn	drought; dryness; misfortune; bad luck; unlucky
2	Chinese	恨	—

Every word from Proto-Indo-European óynos →Every word from Old Latin noenum →Every word from Latin nōn →