Definition of "essential" in English

adjective

1. Necessary.

2. Very important; of high importance.

3. (biology) Necessary for survival but not synthesized by the organism, thus needing to be ingested.

4. Being in the basic form; showing its essence.

   • Don’t mind him being grumpy. That’s the essential Fred.

5. Really existing; existent.

6. (geometry) Such that each complementary region is irreducible, the boundary of each complementary region is incompressible by disks and monogons in the complementary region, and no leaf is a sphere or a torus bounding a solid torus in the manifold.

7. (medicine) Idiopathic.

   • essential blepharospasm

8. Having the nature of essence; not physical.

noun

1. A necessary ingredient.

2. A fundamental ingredient.