* Adjective: This is the most common usage, describing a quality of something or someone.
* Example: "She gave a brilliant performance."
* Noun: This is less common, but it can refer to something exceptionally bright or intelligent.
* Example: "The scientist was known for his brilliant mind."
* Adverb: This is also less common, but it can mean "very" or "extremely" and modify an adjective or another adverb.
* Example: "The painting was brilliantly colored."
So, to know the specific part of speech, you need to look at the context of the sentence.