1. necessary, indispensable

2. essential, basic

3. refined, essential

n.

1. elements, points

2. essence, essence, adverb essential, name essential, essentiality, these adjectives all have the meaning of "basic, basic".

Basic common words refer to a clear and concrete foundation or starting point.

Essential tone is stronger than basic and fundamental, and emphasis is essential, implying that something loses its essential characteristics if it lacks a certain part.

Fundamental written words, not as widely used as basic, focus on abstract things that are basic and fundamental.

Radical focuses on the root or source of something.

Vital is a formal word, focusing on what is essential to maintain life and vitality, or what is vital to life and death. These adjectives all mean "essential".

Indispensable has a strong tone, focusing on absolute necessity or indispensability.

Essential refers to the decisive importance to the nature of the thing itself, which implies that it is indispensable, otherwise it cannot exist.

Necessary is the most commonly used word, focusing on a certain need determined by objective factors, emphasizing inevitability, but not absolutely indispensable.

Necessary is a formal word, especially the need to achieve a certain purpose or get a certain result, and sometimes it can be used interchangeably with necessary. Both adjectives mean "intrinsic and essential".

Inherent refers to a characteristic inherent in an object that cannot be separated from it.

Essential refers to the key factor that determines the existence of the thing. ,absolutely necessary; vitally necessary,absolutely required and not to be used up or sacrificed,anything indispensable, being or relating to or containing the essence of a plant etc,basic and fundamental,of the greatest importance, Defining rights and duties as opposed to giving the rules by which rights and duties are established, essential for vt. is indispensable for ... Essential to vt. is indispensable to, necessary to, essential for vt. is essential to, it is essential that, essential to, essential features, Essential association is basically combined, essential component, essential constant, essential fructosuria, essential a. 1. necessary, essential 2. essential, Basic 3. refined n. 1. elements, point 2. essential, essential adj. unimportant, essential n. standard elements