Where does “excusable” come from?

Excusable comes from Old French escusable, from Latin excusabilis, meaning "able to be excused."

excusable (English): possible to excuse

Definitions

Step	Language	Word	Meaning
1	Old French	escusable	—
2	Latin	excusabilis	—
3	Latin	-bilis	-ble
4	Proto-Italic	-ðlis	—
5	Proto-Indo-European	-dʰlis	—
6	Proto-Indo-European	-dʰlom	Alternative form of *-trom; instrumental suffix;...

excusable — Etymology, Origin & Word History | Etymology Explorer