Word Origin & History
O.E. belt, from P.Gmc. *baltjaz (cf. O.H.G. balz, O.N. balti, Swed. bälte), an early borrowing from L. balteus "girdle, sword belt," said by Varro to be an Etruscan word. As a mark of rank or distinction, mid-14c.; references to boxing championship belts date from 1812. Transferred sense of "broad
stripe encircling something" is from 1660s. Below the belt "unfair" (1889) is from pugilism. To get something under (one's) belt is to get it into one's stomach.
"to thrash as with a belt," 1640s, from belt
(n.); general sense of "to hit, thrash" is attested from 1838.