c.1300, from Old French baril (12c.) "barrel, cask, vat," with cognates in all Romance languages (e.g. Italian barile, Spanish barril), but origin uncertain; perhaps from Gaulish, perhaps somehow related to bar (n.1). Meaning "metal tube of a gun" is from 1640s. Barrel roll in aeronautics is from 1927.
mid-15c., "to put in barrels," from barrel (n.). Meaning "to move quickly" is 1930, American English slang, perhaps suggestive of a rolling barrel. Related: Barreled; barreling.
In a helpless situation: I knew enough about him that I had him over a barrel
[1939+; perhaps fr the tying over a barrel of a person about to be flogged]
a vessel used for keeping flour (1 Kings 17:12, 14, 16). The same word (cad) so rendered is also translated "pitcher," a vessel for carrying water (Gen. 24:14; Judg. 7:16).