bargainyoudaoicibaDictYouDict[bargain 词源字典]
bargain: [14] Bargain appears to be distantly related to borrow. Its immediate source was Old French bargaignier ‘haggle’, but this was probably borrowed from Germanic *borganjan, a derivative of *borgun (from which ultimately we get borrow). The sense development may have been as follows: originally ‘look after, protect’ (the related Germanic *burg- produced English borough, which to begin with meant ‘fortress’, and bury); then ‘take on loan, borrow’; then ‘take or give’; and hence ‘trade, haggle, bargain’.
=> belfrey, borough, borrow, bury[bargain etymology, bargain origin, 英语词源]
belfryyoudaoicibaDictYouDict
belfry: [13] Etymologically, belfry has nothing to do with bells; it was a chance similarity between the two words that led to belfry being used from the 15th century onwards for ‘bell-tower’. The original English form was berfrey, and it meant ‘movable seige-tower’. It came from Old French berfrei, which in turn was borrowed from a hypothetical Frankish *bergfrith, a compound whose two elements mean respectively ‘protect’ (English gets bargain, borough, borrow, and bury from the same root) and ‘peace, shelter’ (hence German friede ‘peace’); the underlying sense of the word is thus the rather tautological ‘protective shelter’.

A tendency to break down the symmetry between the two rs in the word led in the 15th century to the formation of belfrey in both English and French (l is phonetically close to r), and at around the same time we find the first reference to it meaning ‘bell-tower’, in Promptorium parvulorum 1440, an early English-Latin dictionary: ‘Bellfray, campanarium’.
=> affray, bargain, borrow, borough, bury, neighbour