I. verbal auxiliary
1.
Synonyms: want 3, ought, should
2.
--used to indicate requirement by immediate or future need or purpose
we must hurry if we want to catch the bus
Synonyms: have, ||mun, need
Related Word: ought, should want
Idioms: have got to, must needs
II. noun
1.
Synonyms: obligation 2, charge, commitment, committal, devoir, duty, need, ought, ||right
2.
Synonyms: essential 2, condition, necessity, precondition, prerequisite, requirement, requisite, sine qua non