Definitions

1. verb

to have a strong need or obligation to do something

“She must finish her project by tomorrow.”

2. verb

to be necessary or required

“You must wear a seatbelt when driving.”

3. noun

something that is necessary or obligatory

“Happiness is what we must strive for in life.”

4. interjection

an expression used to emphasize a statement or command

“You must be joking!”