bellowsyoudaoicibaDictYouDict[bellows 词源字典]
bellows: [OE] Bellows and belly were originally the same word, Old English belig, which meant ‘bag’. This was used in the compound blǣstbelig, literally ‘blowing bag’, a device for blowing a fire, which was replaced in the late Old English period by the plural form of the noun, belga or belgum, from which we get bellows. Meanwhile the meaning of belly developed from ‘bag’ to, in the 13th century, ‘body’ and, in the 14th century, ‘abdomen’.

Ultimately the word goes back to Germanic *balgiz ‘bag’, from the base *balg- or *belg- (itself a descendant of Indo-European *bhel- ‘swell’), which also lies behind billow [16], bolster, and possibly bellow and bell.
=> bell, bellow, belly, billow, bold, bolster[bellows etymology, bellows origin, 英语词源]
bellows (n.)youdaoicibaDictYouDict
c. 1200, belwes, "a bellows," literally "bags," plural of belu, belw, northern form of beli, from late Old English belg "bag, purse, leathern bottle" (see belly (n.)). Reduced from blæstbælg, literally "blowing bag." Used exclusively in plural since 15c., probably due to the two handles or halves.