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.
Innate, inherent, inseparable from the thing itself, essential.
Built-in.
Situated, produced, secreted in, or coming from inside an organ, tissue, muscle or member.
A built-in function that is implemented directly by the compiler, without any intermediate call to a library.
An ability possessed by a character and not requiring any external equipment.