abound (v.)
early 14c., from Old French abonder "to abound, be abundant, come together in great numbers" (12c.), from Latin abundare "overflow, run over," from Latin ab- "off" (see ab-) + undare "rise in a wave," from unda "water, wave" (see water (n.1)).
What is the meaning of "off", while during a "rise in a wave" ? Is there some hypotaxis?