Where does “Base” come from?

Base comes from Latin basis, meaning "foundation" or "step," which underwent sound changes as it passed through Old French and Middle English before arriving in modern English.

Ancestry of “Base”, step by step

Step	Language	Word	Meaning
1	Middle English	base	A foundation or base; the bottom of a building;...
2	Old French	base	base
3	Latin	basis	A pedestal, foot, base; basis, foundation; The...
4	Ancient Greek	βάσις	step; rhythm; foot
5	Proto-Hellenic	gʷə́tis	step
6	Proto-Indo-European	gʷémtis	step, act of walking
7	Proto-Indo-European	gʷem-	to step

Every word from Proto-Indo-European gʷem- →

Base — Etymology, Origin & Word History | Etymology Explorer