Where does “decimoprimo” come from?

decimoprimo (Italian) comes from Italian decimo, from Latin Decimus, from Latin decem, from Latin -nus, from Proto-Italic -nos, from Proto-Indo-European -nós — Creates verbal adjectives from roots.

decimoprimo (Italian): eleventh

Definitions

eleventh

Ancestry of “decimoprimo”, step by step

decimoprimo traces back through two separate lines of ancestry.

via Italian decimo

Step	Language	Word	Meaning
1	Italian	decimo	tenth; first-person singular present of decimare
2	Latin	Decimus	originally used for a tenth-born son
3	Latin	decem	ten; 10
4	Latin	-nus	-an
5	Proto-Italic	-nos	Creates verbal adjectives from verb stems
6	Proto-Indo-European	-nós	Creates verbal adjectives from roots

via Italian Primo

Step	Language	Word	Meaning
1	Italian	Primo	often given to firstborns
2	Latin	prīmus	—
3	Latin	prīsmos	—
4	Proto-Italic	priisemos	foremost, first
5	Proto-Indo-European	per-	before, in front; first; to go through
6	Proto-Indo-European	pr̥tós	passed , crossed

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