by 1650s, "of or pertaining to Abdera," in Thrace, whose citizens were proverbial as provincials who would laugh at anything or anyone they didn't understand (Abderian laughter), making their town the Hellenic equivalent of Gotham (q.v.). Especially (or alternatively) as it was the birthplace of Democritus the atomist, the "Laughing Philosopher" (born c. 460 B.C.E.) who observed human follies.
1670s, "a bottom, the bottom; foundation, groundwork," from French fond "a bottom, floor, ground" (12c.), also "a merchant's basic stock or capital," from Latin fundus "bottom, foundation, piece of land" (from PIE root *bhudh- "bottom, base," source also of Sanskrit budhnah, Greek pythmen "foundation, bottom," Old English botm "lowest part;" see bottom (n.)). Meaning "stock of money or wealth available for some purpose" is from 1690s; sense of "store of anything to be drawn upon" is from 1704. Funds "money at one's disposal" is from 1728.