bonus (n.)
"money or other benefit given as a premium or extra pay to reward or encourage work," 1773, "Stock Exchange Latin" [Weekley], meant as "a good thing," 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." The correct noun form would be bonum. Specifically as "extra dividend paid to shareholders from surplus profits" from 1808. 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, at the height of the Great Depression, demanding early redemption of their service bonus certificates (which carried a maximum value of $625).