Where does “quinceaños” come from?

quinceaños (Spanish) comes from Spanish quince, from Old Spanish quinze, from Latin quindecim, from Latin decem, from Latin -nus, from Proto-Italic -nos, from Proto-Indo-European -nós — Creates verbal adjectives from roots.

quinceaños (Spanish): A Mexican girl’s 15th birthday party

Definitions

A Mexican girl’s 15th birthday party

Ancestry of “quinceaños”, step by step

quinceaños traces back through two separate lines of ancestry.

via Spanish quince

Step	Language	Word	Meaning
1	Spanish	quince	fifteen
2	Old Spanish	quinze	fifteen
3	Latin	quindecim	fifteen; 15
4	Latin	decem	ten; 10
5	Latin	-nus	-an
6	Proto-Italic	-nos	Creates verbal adjectives from verb stems
7	Proto-Indo-European	-nós	Creates verbal adjectives from roots

via Spanish años

Step	Language	Word	Meaning
1	Spanish	años	plural of año; years
2	Old Spanish	anno	year
3	Latin	annus	year; time; season
4	Proto-Italic	atnos	year
5	Proto-Indo-European	h₂et-no-	—
6	Proto-Indo-European	h₂et-	grass

Every word from Proto-Indo-European -nós →Every word from Latin -nus →Every word from Latin decem →