O.E.
belg, bylg (W.Saxon),
bælg (Anglian) "leather bag, purse, bellows," from P.Gmc.
*balgiz "bag" (cf. O.N.
belgr "bag, bellows,"
bylgja "billow," Goth.
balgs "wineskin"), from PIE
*bhelgh- "to swell," extension of root
*bhel- "to inflate, swell" (see
bole). Meaning shifted to "body" (c.1275), then to "abdomen" (1340). Meaning "bulging part or concave surface of anything" is 1591; the verb "to swell out" is from 1624. The W.Gmc. root had an extended sense of "anger, arrogance" (cf. O.E.
bolgenmod "enraged;"
belgan (v.) "to become angry").
Belly-button for "navel" is from 1877.
Bellyache (v.) in the slang sense of "complain" is first recorded 1888.
Belly-dance (1899) translates Fr.
danse du ventre.