A perfectionist was someone who was not satisfied with their own efforts until they had achieved perfection.
After noting Kathryn Janeway's displeasure at his attempts to cook for her in 2377, Jaffen described himself as a perfectionist and said he would keep trying to until he made her the perfect meal. Janeway declined the offer, saying she'd rather prepare the food herself than cease eating with him after he had mastered the task. (VOY: "Workforce")