Where does “semana” come from?

semana (Bikol Central) comes from Spanish semana, from Old Spanish semana, from Latin septimāna, from Latin septimānus, from Latin septimus, from Latin Septem, from Proto-Italic septem, from Proto-Indo-European septḿ̥ — seven.

Ancestry of “semana”, step by step

Step	Language	Word	Meaning
1	Spanish	semana	week
2	Old Spanish	semana	—
3	Latin	septimāna	week
4	Latin	septimānus	of or pertaining to the seventh in a series
5	Latin	septimus	seventh
6	Latin	Septem	seven; 7
7	Proto-Italic	septem	seven
8	Proto-Indo-European	septḿ̥	seven

Every word from Proto-Indo-European septḿ̥ →Every word from Proto-Italic septem →Every word from Latin Septem →