See incidental in Webster's New World College Dictionary
adjective
happening as a result of or in connection with something more important; casual: incidental benefits
likely to happen as a result or concomitant: with to: troubles incidental to divorce
secondary or minor, but usually associated: incidental expenses
noun
something incidental
miscellaneous or minor items or expenses
See incidental in American Heritage Dictionary 4
(ĭnˌsĭ-dĕnˈtl)
adjective
Occurring or likely to occur as an unpredictable or minor accompaniment: the snags incidental to a changeover in upper management. See Synonyms at accidental.
Of a minor, casual, or subordinate nature: incidental expenses.
noun
A minor accompanying item or expense: a pocket in the suitcase for incidentals.