Etymology

From , past tense of . Cognate with Dutch and and with German .

Verb

1. To do with certainty;

   If it rained all day, it must be very wet outside.

   You picked one of two, and it wasn't the first: it must have been the second.

2. To do as a requirement; .

   You must arrive in class on time. — the requirement is an imperative

   This door handle must be rotated fully. — the requirement is a directive

Usage notes

Compare with weaker auxiliary verb , indicating a strong probability of the predicate's execution. Compare with weaker auxiliary verb , indicating mere intent for the predicate's execution; and stronger auxiliary verb , indicating that the negative consequence will be unusually severe. is not used to indicate obligation in the past. As indicated above, the usual form is . It is possible to use for the past also. For this reason, and are also used as alternatives to in the present and future.

Noun

1. Something that exhibits the property of being stale or musty
2. Fruit juice that will ferment or has fermented, usually grapes
3. A time during which male elephants exhibit increased levels of sexual activity and aggressiveness (also musth).
4. Something that is mandatory or required.

   If you'll be out all day, sunscreen is a must.