* Noun: When "bonus" refers to something extra given in addition to what is usual or expected, it's a noun.
* Example: "She received a bonus for exceeding her sales quota."
* Adjective: When "bonus" describes something as being an extra or added benefit, it's an adjective.
* Example: "We have a bonus feature on our new phone."
So, it's important to look at the context of the sentence to determine which part of speech "bonus" is.