O.E.
belle, common North Sea Gmc. (cf. M.Du.
belle, M.L.G.
belle) but not found elsewhere in Gmc. (except as a borrowing), from PIE base
*bhel- "to sound, roar."
Bellhop is a 1910 shortening of
bellhopper (1900), from the notion of hopping to action at the ring of the bell.
Bell-boy was originally (1851) a ship's bell-ringer, later (1861) a hotel page.
Bell-wether (c.1440; see
wether) was "the leading sheep of a flock, on whose neck a bell is hung;" used earlier in the fig. sense of "chief, leader" (c.1430).
Bell-bottomed trousers first recorded 1891.
Bell, book, and candle is a reference to a form of excommunication. To
ring a bell "awaken a memory," 1934, is perhaps a reference to Pavlovian experiments.
[bel] 
n]