bonus (n.) Look up bonus at Dictionary.com
1773, "Stock Exchange Latin" [Weekley], from Latin bonus "good" (adj.), perhaps originally "useful, efficient, working," from Proto-Italic *dw-eno- "good," probably a suffixed form of PIE root *deu- (2) "to do, perform; show favor, revere." The correct noun form would be bonum. In U.S. history the bonus army was tens of thousands of World War I veterans and followers who marched on Washington, D.C., in 1932 demanding early redemption of their service bonus certificates (which carried a maximum value of $625).