The chapter "Emotion" from the National Cancer Institute's NCI Thesaurus defines emotion as the aspect of consciousness that is devoted to affect or feeling. It describes it as a strong feeling, an aroused mental state, or an intense state of drive or unrest directed toward a definite object, characterized by physiological, somatic, and behavioral components.The chapter "Emotion" from the National Cancer Institute's NCI Thesaurus defines emotion as the aspect of consciousness that is devoted to affect or feeling. It describes it as a strong feeling, an aroused mental state, or an intense state of drive or unrest directed toward a definite object, characterized by physiological, somatic, and behavioral components.