must (
http://definr.com/must)
adj : highly recommended; "a book that is must reading" [syn:
must(a)]
v 1: be obliged, required, or forced to; "She has to get her
driver's license" [syn:
have,
have got,
need]
2: be logically necessary [syn:
should,
ought,
need]
3: be likely or probable; "They have to be kidding" [syn:
have]