ought

The word “ought” means used to express what is the right or sensible thing to do, or what is likely to be true. In plain terms, a slightly formal way of saying "should," for duty, advice, or likelihood.

“Ought” is pronounced awt (/ɔt/ in IPA).

Here is “ought” used in a sentence: “You ought to see a doctor about that cough.”

“Ought” is a verb.

The word “ought” comes from Old English. From Old English āhte, an old past-tense form of "owe" — originally meaning something closer to "was obligated to.".

“Ought” is a fairly common word in modern English.

"Ought" and "should" both express duty, advice, or expectation and are often interchangeable, as in "you ought to rest" and "you should rest." "Ought" is slightly more formal and always takes "to" before the following verb, whereas "should" does not. In everyday speech, "should" is far more common.

Yes, "ought" is almost always followed by "to" plus the base verb, as in "you ought to call her." This makes it unusual, since "should," "must," and "can" are not followed by "to." The main exception is short replies where the verb is understood, such as "You ought to apologize — yes, I ought."

The negative is formed with "ought not to," as in "you ought not to worry," and the contracted "oughtn't to" appears in informal British English. In casual speech, many people avoid the negative of "ought" altogether and use "shouldn't" instead. The "to" is normally kept even in the negative.

"Ought to" expresses advice, recommendation, or expectation, leaving the listener some choice, as in "you ought to see a doctor." "Must" expresses stronger obligation or necessity with less room for choice, as in "you must see a doctor." "Ought to" is therefore softer and less forceful than "must."