In·ci·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*ci*den*tal*ly, adv. -- In*ci*den*tal*ness, n.
I treat either or incidentally of colors. --Boyle.