Where does “decimal” come from?

decimal (Romanian) comes from French décimal, from Medieval Latin decimalis, from Latin Decimus, from Latin decem, from Latin -nus, from Proto-Italic -nos, from Proto-Indo-European -nós — Creates verbal adjectives from roots.

Ancestry of “decimal”, step by step

Step	Language	Word	Meaning
1	French	décimal	decimal
2	Medieval Latin	decimalis	—
3	Latin	Decimus	originally used for a tenth-born son
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

Words derived from “decimal”

zecimală

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