Dictionarymustinferred certainty
verb

must

Be almost certainly true based on evidence or reasoning

The lights are on, so someone must be home.

Etymology

The inherited modal developed from permission and necessity. In reasoning, necessity becomes a strong inference: the evidence makes the stated conclusion seem unavoidable.

More examples

  • You must be exhausted after that long drive.
  • He must have missed the last bus.
  • That must be the package we ordered.

Forms

must