Other forms: bonuses
A bonus is extra money on top of the pay you were already promised, given for good results. The Christmas bonus at the bank, the five hundred pounds for finishing early, the signing bonus that talks someone into taking the job.
Away from pay, a bonus is any good thing you were not counting on: the flat came with a garden, which was a bonus. It works in front of other nouns too, giving a bonus track, a bonus level, bonus points. The plural is bonuses, with -es on the end. And keep it apart from a pay rise: a rise lifts your salary for good, while a bonus is paid once and then it is gone.
1nounbonusExtra money paid on top of normal wages, for good results or at a set time of year.
“Everyone on the team got a bonus that December.”
synonyms: perk
2noungoodAny good thing you get without expecting it.
“The flat came with a parking space, which was a real bonus.”
3adjectiveaddedExtra, added to what was expected.
“The album has two bonus tracks at the end.”
Too few real examples of this word to estimate which sense is commonest.
bonus is a payment.
Latin
bonus — good
English, today
bonus
Borrowed from Latin bonus (“good”). a doublet of bona.
Etymology from Wiktionary, CC BY-SA