* Adjective: This is the most common use, describing something that is exceptionally intelligent, impressive, or beautiful.
* Example: "She gave a brilliant presentation."
* Noun: This is less common, but it can refer to a very bright light or a very intelligent person.
* Example: "The diamond was a brilliant."
* Adverb: This is even less common, but "brilliant" can be used to describe how something is done.
* Example: "She sang the song brilliantly."
Therefore, you need to consider the context of the sentence to determine the specific part of speech.