ORIGIN OF MUST - Middle English moste, from Old English mōste, past indicative & subjunctive of mōtan to be allowed to, have to; akin to Old High German muozan to be allowed to, have to First Known Use: before 12th century
Definition of must (verb) \məs(t), ˈməst\
used to say that something is required by a rule or law ("You must present your passport.")
used to say that someone should do something ("We must hurry to the airport.")
used to say that something is very likely ("You must be John.")
Which meaning developed first in the English Language, "strong obligation" or "certainty"?