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