essential

essential [ə sen′shəl, isen′shəl]

adj.

[ME essencial < LL essentialis: see ESSENCE]

1. of or constituting the intrinsic, fundamental nature of something; basic; inherent [an essential difference]

2. absolute; complete; perfect

3. absolutely necessary; indispensable; requisite

4. containing, or having the properties of, a concentrated extract of a plant, drug, food, etc. [an essential oil]

5. Biochem. needed for life or health but not synthesized within the body, as an amino acid or vitamin that must be consumed

n.

something necessary or fundamental; indispensable, inherent, or basic feature or principle

essentially

adv.

SYN.- ESSENTIAL, in strict usage, is applicable to that which constitutes the absolute essence or the fundamental nature of a thing and therefore must be present for the thing to exist, function, etc. [food is essential to life ]; an INDISPENSABLE person or thing cannot be done without if the specified or implied purpose is to be achieved; REQUISITE is applied to that which is required by the circumstances or for the purpose and generally suggests a requirement that is imposed externally rather than an inherent need [the requisite experience for a position ]; NECESSARY implies a pressing need but does not always connote absolute indispensability