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must¹

(mŭst)

v.aux.

1. To be obliged or required by morality, law, or custom: Citizens must register in order to vote.

2. To be compelled, as by a physical necessity or requirement: Plants must have oxygen in order to live.

3. Used to express a command or admonition: You must not go there alone. You simply must be careful.

4. To be determined to; have as a fixed resolve: If you must leave, do it quietly.

a. Used to indicate inevitability or certainty: We all must die.

b. Used to indicate logical probability or presumptive certainty: If the lights were on, they must have been at home.

v.intr.
Archaic

To be required or obliged to go: "I must from hence" (Shakespeare).

Something that is absolutely required or indispensable: Promptness on the job is a must. Comfortable boots are a must when going on a hike.

[Middle English moste, from Old English mōste, past tense of mōtan, to be allowed; see med- in the Appendix of Indo-European roots.]

must²

(mŭst)

The quality or condition of being stale or musty.

[Probably back-formation from MUSTY.]

must³

(mŭst)

The unfermented or fermenting juice expressed from fruit, especially grapes.

[Middle English, from Old English, from Latin mustum, from neuter of mustus, new, fresh.]

must⁴

(mŭst)

Variant of musth.

must⁵

(mŭst)

Musk.

[Scottish, from Old French, variant of musc; see MUSK.]

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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