"hollow metallic instrument which rings when struck," Old English belle, which has cognates in Middle Dutch belle, Middle Low German belle but is not found elsewhere in Germanic (except as a borrowing); apparently from PIE root *bhel- (4) "to sound, roar" (compare Old English bellan "to roar," and see bellow).
As a division of daily time aboard a ship, by 1804, from its being marked by bells struck every half hour. Statistical bell curve is by 1920, said to have been coined was coined 1870s in French. Of glasses in the shape of a bell from 1640s. Bell pepper is from 1707, so called for its shape. Bell, book, and candle is a reference to a form of excommunication (the bells were rung out of order and all together to signify the loss of grace and order in the soul of the excommunicated).
To ring a bell "awaken a memory" (1934) is perhaps a reference to Pavlovian experiments; it also was a signal to summon a servant (1782).
"attach a bell to," late 14c., from bell (n.). Related: Belled; belling. Allusions to the story of the mice that undertook to bell the cat (so they can hear him coming) date to late 14c.