Synonyms of the word

must

• v. (modal auxiliary, defective) To do with certainty; indicates that the speaker is certain that the subject…
• v. (modal auxiliary, defective) To do as a requirement; indicates that the sentence subject is required as…
• n. Something that is mandatory or required.
• n. The property of being stale or musty.
• n. Something that exhibits the property of being stale or musty.
• n. Fruit juice that will ferment or has fermented, usually grapes.
• v. (transitive) To make musty.
• v. (intransitive) To become musty.
• n. A time during which male elephants exhibit increased levels of sexual activity and aggressiveness (also…
• n. An elephant in this sexual and aggressive state.

essential

• adj. Necessary.
• adj. Very important; of high importance.
• adj. (biology) necessary for survival but not synthesized by the organism, thus needing to be ingested.
• adj. Being in the basic form; showing its essence.
• adj. Really existing; existent.
• adj. (of a lamination of a 3-manifold) Such that each complementary region is irreducible, the boundary of…
• adj. (medicine) Idiopathic.
• n. A necessary ingredient.
• n. A fundamental ingredient.

moldiness

• n. The state or degree of being moldy.

mustiness

• n. The characteristic of being musty.

necessary

• adj. Required, essential, whether logically inescapable or needed in order to achieve a desired result or avoid…
• adj. Unavoidable, inevitable.
• adj. (obsolete) Determined, involuntary: acting from compulsion rather than free will.
• n. (Britain, archaic euphemistic, usually with the definite article) A place to do the "necessary" business…

necessity

• n. The quality or state of being necessary, unavoidable, or absolutely requisite.
• n. The condition of being needy; desperate need; lack.
• n. Something necessary; a requisite; something indispensable.
• n. Something which makes an act or an event unavoidable; an irresistible force; overruling power.
• n. The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual,…
• n. (law) Greater utilitarian good; used in justification of a criminal act.
• n. (law, in the plural) Indispensable requirements (of life).

requirement

• n. A necessity or prerequisite; something required or obligatory. Its adpositions are generally of in relation…
• n. Something asked.
• n. (engineering) A statement (in domain specific terms) which specifies a verifiable constraint on an implementation…

requisite

• adj. Essential, required, indispensable.
• n. An indispensable item; a requirement.

staleness

• n. (uncountable) The state or quality of being stale.
• n. (countable) The result or product of being stale.