Where does “seze” come from?

seze (Old French) comes from Latin sedecim, from Latin decem, from Latin -nus, from Proto-Italic -nos, from Proto-Indo-European -nós — Creates verbal adjectives from roots.

Ancestry of “seze”, step by step

Step	Language	Word	Meaning
1	Latin	sedecim	sixteen; 16
2	Latin	decem	ten; 10
3	Latin	-nus	-an
4	Proto-Italic	-nos	Creates verbal adjectives from verb stems
5	Proto-Indo-European	-nós	Creates verbal adjectives from roots

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