[muhs-uh nt]

contraction of must not.

Nearby words

  1. muster,
  2. muster day,
  3. muster in,
  4. muster roll,
  5. musth,
  6. musty,
  7. mut,
  8. mut dash,
  9. mut.,
  10. mutability

Usage note Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Word Origin and History for mustn't


by mid-18c., contraction of must not; see must (v).

Online Etymology Dictionary, © 2010 Douglas Harper