belonging to the essence, or that which makes an object, or class of objects, what it is.-hence, really existing; existent.-important in the highest degree; indispensable to the attainment of an object; indispensably necessary.-containing the essence or characteristic portion of a substance, as of a plant; highly rectified; pure; hence, unmixed; as, an essential oil.-necessary; indispensable; -- said of those tones which constitute a chord, in distinction from ornamental or passing tones.-idiopathic; independent of other diseases.