nonessential

1. Having little or no importance; not essential.
2. Biochemistry. Being a substance that is required for normal functioning but does not need to be included in the diet because of the body's ability to synthesize it from other nutrients.

adjective

Not necessary: dispensable, inessential, needless, uncalled-for, unessential, unnecessary, unneeded, unrequired. See necessary/unnecessary.

Definition: not needed or important
Antonyms: essential, important, indispensable, necessary, needed

Being a substance required for normal functioning but not needed in the diet because the body can synthesize it.

The noun has one meaning:

Meaning #1: anything that is not essential
  Synonym: inessential

The adjective nonessential has one meaning:

Meaning #1: not of prime or central importance
  Synonym: incidental