Source : Webster's Revised Unabridged Dictionary (1913)

Unessential \Un`es*sen"tial\, a.
   1. Not essential; not of prime importance; not indispensable;
      unimportant. --Addison.

   2. Void of essence, or real being. [R.] --Milton.

Unessential \Un`es*sen"tial\, n.
   Something not constituting essence, or something which is not
   of absolute necessity; as, forms are among the unessentials
   of religion.

Source : WordNet®

unessential
     adj : not basic or fundamental [syn: {inessential}] [ant: {essential}]