Imperative
Part of speech: noun
Definition: The grammatical mood expressing an order (see jussive). In English, the imperative form of a verb is the same as that of the bare infinitive. A verb in imperative mood. An essential action, a must: something which is imperative.
Part of speech: adjective
Definition: essential Having a semantics that incorporates mutable variables.
Example sentence: As the world we live in is so unpredictable, the ability to learn and to adapt to change is imperative, alongside creativity, problem-solving, and communication skills.
Insistent
Part of speech: adjective
Definition: Standing or resting on something.Urgent in dwelling upon anything; persistent in urging or maintaining.Extorting attention or notice; coercively staring or prominent; vivid; intense.Standing on end: specifically said of the hind toe of a bird when its base is inserted so high on the shank that only its tip touches the ground: correlated with incumbent.