ought not to ... Definition

ought
auxiliary verb

1. Used to express: duty or obligation.

Example: You ought to help if you can
Thesaurus: should, have to, be required, must.
2. Used to express: advisability.

Example: You ought to see a doctor
3. Used to express: probability or expectation.

Example: She ought to be here soon
4. Used to express: shortcoming or failure.

Example: He ought to have been here hours ago
5. Used to express: enthusiastic desire on the part of the speaker.

Example: You really ought to read this book
6. Used to express: logical consequence.

Example: The answer ought to be ‘four'

Idiom: ought not to ...

Used to express moral disapproval.
Example: You ought not to speak to him like that

Etymology: Anglo-Saxon ahte, past tense of agen to owe.