(used to express duty or moral obligation)

Every citizen ought to help.

(used to express justice, moral rightness, or the like)

He ought to be punished. You ought to be ashamed.

(used to express propriety, appropriateness, etc.)

You ought to be home early. We ought to bring her some flowers.

(used to express probability or natural consequence)

That ought to be our train now.

duty or obligation.