Meaning of ESSENTIAL in English
adj hence, really existing; existent.
2. essential ·adj idiopathic; independent of other diseases.
3. essential ·adj belonging to the essence, or that which makes an object, or class of objects, what it is.
4. essential ·adj important in the highest degree; indispensable to the attainment of an object; indispensably necessary.
5. essential ·adj necessary; indispensable;
said of those tones which constitute a chord, in distinction from ornamental or passing tones.
6. essential ·adj containing the essence or characteristic portion of a substance, as of a plant; highly rectified; pure; hence, unmixed; as, an essential oil.
Webster English vocab. Английский словарь Webster. 2012