I. ˈȯt verbal auxiliary
Etymology: Middle English oughte (1st & 3d singular present indicative), from oughte, 1st & 3d singular past indicative & subjunctive of owen to own, owe — more at owe
Date: 12th century
— used to express obligation
ought to pay our debts
advisability
ought to take care of yourself
natural expectation
ought to be here by now
or logical consequence
the result ought to be infinity
II. ˈȯ(ḵ)t transitive verb
Etymology: Middle English oughte, 1st & 3d singular past indicative of owen
Date: 13th century
1. chiefly Scottish : possess
2. chiefly Scottish : owe
III. ˈȯt noun
Date: 1678
: moral obligation : duty
IV. ˈȯt, ˈät
archaic variant of aught