late 14c., "action of founding," from Old French fondacion "foundation" (14c.) or directly from Late Latin fundationem (nominative fundatio) "a founding," noun of action from past-participle stem of Latin fundare "to lay a bottom or foundation" (see found (v.1)). The Latin word is glossed in Old English by staþol.
Specialized sense of "establishment of an institution with an endowment to pay for it" is from late 14c.; meaning "that which is founded" (a college, hospital, etc.) is from 1510s; meaning "funds endowed for benevolent or charitable purposes" is from early 15c. Sense of "solid base of a structure" is from early 15c.