To be under moral obligation to be or do.
To be fitting or imperative.
Aught; anything.
What do you think I ought to do? – Andy Grant's Pluck by Horatio Alger
Well, I ought to be. – A Day Of Fate by E. P. Roe
She ought to be here by this time. – Foul Play by Charles Reade Dion Boucicault