Pronunciation: (ôt),[key]auxiliary verb. 1. (used to express duty or moral obligation): Every citizen ought to help. 2. (used to express justice, moral rightness, or the like): He ought to be punished. You ought to be ashamed. 3. (used to express propriety, appropriateness, etc.): You ought to be home early. We ought to bring her some flowers. 4. (used to express probability or natural consequence): That ought to be our train now.