Source : Webster's Revised Unabridged Dictionary (1913)

Incindental \In`cin*den"tal\, a.
   Happening, as an occasional event, without regularity; coming
   without design; casual; accidental; hence, not of prime
   concern; subordinate; collateral; as, an incidental
   conversation; an incidental occurrence; incidental expenses.

         By some, religious duties . . . appear to be regarded .
         . . as an incidental business.           --Rogers.

   Syn: Accidental; casual; fortuitous; contingent; chance;
        collateral. See {Accidental}. -- {In`cen*den"tal*ly},
        adv. -- {In`cen*den"tal*ness}, n.

              I treat either or incidentally of colors. --Boyle.