bounce:  Bounce is something of a mystery word. When it first appears in Middle English it means ‘hit’, and it does not acquire its modern sense ‘rebound’ until the late 16th century. There are similar words in other Germanic languages, such as Dutch bons ‘thump’, but there is no reason to suppose that any of them is actually the source of the English word. Many etymologists incline to the view that bounce is an independent onomatopoeic formation.
early 13c., bounsen "to thump, hit," perhaps from Dutch bonzen "to beat, thump," or Low German bunsen, or imitative; sense probably influenced by bound (v.). Sense of "to bounce like a ball" is from 1510s; the rubber check sense is from 1927. Related: Bounced; bouncing.