Wikipedia entry for 'Dumbbell'
“Dumbbells” as a word originated in Tudor England – athletes used hand-held church bells to develop the upper body and arms. These bells ranged in weight from a few ounces to many pounds. The bells were flourished in various ways. This would have made a great deal of noise, so the athletes would take out the clappers so they could practice quietly; hence the name “dumb”, as in “no sound”, and “bell” – dumbbell. When strongmen started to make their own equipment, they kept the name, even though the shape changed.
