bon adj.

"money or other benefit given as a premium or extra pay to reward or encourage work," 1773, a phrase in "Stock Exchange Latin" [Weekley], taken 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 the name given to the 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).

"witticism, clever or witty saying," 1735, French, literally "good word," from bon "good" + mot "remark, short speech," literally "word" (12c.), from Vulgar Latin *muttum, from Latin muttire "to mutter, mumble, murmur" (see mutter (v.)). The plural is bons mots.