Must
Part of speech: verb
Definition: To do with certainty; . To do as a requirement; .
Part of speech: noun
Definition: Something that is mandatory or required. Something that exhibits the property of being stale or musty. Fruit juice that will ferment or has fermented, usually grapes. A time during which male elephants exhibit increased levels of sexual activity and aggressiveness (also musth).
Example sentence: Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same.
Essential
Part of speech: adjective
Definition: Necessary.Very important; of high importance.Being in the basic form; showing its essence.Such that each complementary region is irreducible, the boundary of each complementary region is incompressible by disks and monogons in the complementary region, and no leaf is a sphere or a torus bounding a solid torus in the manifold.
Part of speech: noun
Definition: A necessary ingredient.A fundamental ingredient.
Example sentence: I do not think that there is any other quality so essential to success of any kind as the quality of perseverance. It overcomes almost everything, even nature.