Where does “bonus” come from?

Bonus comes from Latin bonus, from earlier Latin duonus, from Proto-Italic dwenos, from Proto-Indo-European dew-, a root of uncertain meaning.

bonus (English): Something extra that is good; an added benefit;...

Definitions

Step	Language	Word	Meaning
1	Latin	bonus	good, honest, brave, noble, kind, pleasant;...
2	Old Latin	duenos	Alternative form of duonus
3	Proto-Italic	dwenos	good
4	Proto-Indo-European	dew-	to show favour, revere; to fail, to lag, to be...