Having the nature of essence; not physical.
Necessary.
Necessary for survival but not synthesized by the organism, thus needing to be ingested.
Being in the basic form; showing its essence.
Really existing; existent.
Very important; of high importance.
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.
Idiopathic.
A necessary ingredient.
A fundamental ingredient.
(of an adjective) Describing a quality that cannot normally be varied because it is extreme (e.g. freezing), absolute (e.g. dead), or classification (e.g. nuclear).
That cannot be graded.
Any adjective that is not gradable.