Final answer:
The word 'petulant' describes a mood characterized by minor irritation and impatience, often in a childish manner. In the given context, it implies that the speaker's request was made out of such irritation.
Step-by-step explanation:
In one of my more petulant moods, I told my noisy roommate to leave me alone and keep the noise down. The term petulant refers to being irritable or annoyed, especially over a petty issue. It often conveys a sense of impatience and can be associated with childish behavior. In the provided context, the use of petulant suggests that the speaker's mood was not the best, and their request to the roommate was made out of irritation.