Definitions:

1. A strong suggestion or recommendation. VERB
   • They had best prepare for the meeting to ensure everything goes smoothly.
2. A way of saying that something is the best course of action. VERB
   • She had best wear a coat; it's going to be very cold outside.
3. Used to give strong advice or a recommendation, implying that a particular action is the most advisable or necessary under the circumstances. VERB
   • He had best apologize for his mistakes before things get worse.
4. Used to indicate that it would be wise or advisable for someone to do something. VERB
   • You had best study for your exams if you want to pass.

Synonyms:

• had better
• Ought to
• should