Synonyms for Essential:

adj.

all (adjective)
indispensable.
basic, fundamental (adjective)
key, elementary, primary, primitive, prime, elemental, underlying, basal, quintessential, constitutional.
central (adjective)
nuclear.
existent (adjective)
extant, ontological, existent, existing, real, present, Subsistent, Subsisting.
focal (adjective)
central, core, key, convergent, nuclear, focal, asymptotic.
important, vital (adjective)
imperative, required, indispensable, constitutive, needful, necessary, requisite, fundamental, prerequisite.
in essence (adjective)
virtual.
instrumental (adjective)
helpful, useful, effectual, instrumental, valuable, principle.
life-and-death (adjective)
all-important.
pure (adjective)
decent, purebred, chaste, spotless, undefiled, simple, unadulterated, stainless, white, aboriginal, bare, undiluted, immaculate, basic, formative, blameless, virtuous, fundamental, prime, indivisible, sinless, monolithic, unalloyed, guiltless, honorable, untainted, angelic, unadorned, basal, uncluttered, atomic, clean, stark, plain, primal, elementary, unsullied, pure, innocent, primary, untarnished, faultless, elemental, Simon-pure, austere, foundational, nascent, unblemished, irreducible, clear.
required (adjective)
indispensable, binding, Stipulated, pressing, inevitable, inescapable, involuntary, compulsory, mandatory, required, inexorable, imperative, obligatory, proviso, constraining, necessary, requisite, prerequisite, must.

n.

healing, well-balanced, healthy, beneficial, sensible, restorative, wholesome, good, therapeutic. element, essence, basis, concern, priority, feature, quintessential, burning issue/question. underlying, primitive, ultimate. important, needful. essential (noun)
basal, virtual, in essence, organic, all-important, primary, no-frills, must, of the essence, vital, biogenic, constituent, requisite, necessity, basic, constitutive, substantial, staple, requirement, substantive, constitutional, necessary, life-sustaining.
necessary (noun)
without fail, at all costs, of necessity.
necessity, basic (noun)
essence, must, principle, requirement, element.
object (noun)
necessity, necessary, requisite, requirement.
requirement (noun)
requirement.

Other synonyms:

integral, beneficial, wholesome, therapeutic. healing, healthy, underlying, well-balanced, element. primitive, ultimate. sensible. raw. good.

Usage examples for essential

  1. Which was the essential truth about Bill Sewall. – Roosevelt in the Bad Lands by Hermann Hagedorn
  2. Seeing him had been perhaps a small mortal joy; but it had not been the tremendous and essential thing. – The Flaw in the Crystal by May Sinclair
  3. Such a definition is not thought essential at the present time. – The Teaching of Geometry by David Eugene Smith