Etymology: Now used only in plural: the singular was still in use in 15th cent., and still later in compounds. The Old English name for ‘bellows’ was blǽstbęl(i)g , blást-bęl(i)g ‘blast-bag, blowing-bag’ (= Old Norse blástr-belgr , Swedish blåsbälg , Danish blæsebælg , modern German blasebalg ); but already in the 11th cent. the simple bęlg , bylg , bylig ‘bag’ occurs in this sense in the glossaries. (So also modern Swedish bälg , and Danish bælger plural = ‘bellows.’) Thence the Middle English beli , bely , buly (ü ), really the same word as belly n., under which see the remoter etymology. In the sense ‘bellows,’ bely was still used in the singular by Chaucer, but after 1400 we find this only with the sense ‘belly,’ though the plural belies, bellies retained the sense ‘bellows’ late in the 16th cent. in literature, and bellis, bellice, is still common in the dialects. But in Wyclif we find another form, belu, belw, in 15th cent. bellowe (apparently of northern or northern midland origin), of which the plural belwes, belowes, bellows became established in 16th cent. as the literary form, bellies being thenceforth used only as the plural of ‘belly’ in the modern sense. In later times bellows has often been construed as a singular, ‘a bellows,’ and occasionally has even received a second plural inflection, bellowses, which is common in the dialects; compare ‘a gallows,’ and obsolete or dialect plural gallowses. Hence also the pronunciation /ˈbɛləs/, the only one known to orthoepists early in the 19th cent., which has subsequently largely given place to /ˈbɛləʊz/. The evidence at present available does not settle whether belu , belw , came down from a non-palatalized form of Old English bęlg , or from the plural inflections bęlga , bęlgum , while beli represented the singular forms bęlig , bęlge (compare Middle English singular dai , dei , plural dawes < Old English dæg , dagas ); or, finally, whether it was a northern English adoption of Old Norse belgr : for each of these hypotheses something may be said. Bellows is apparently not cognate with Latin follis : see ball n.¹ and belly n.

Etymology: < bellows n.