incidental - noun

(frequently plural) an expense not budgeted or not specified

an item that is incidental

incidental - adjective

• (sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence
• not of prime or central importance
• following or accompanying as a consequence

incidental - thesaurus

accompanying   attendant   concomitant   consequent   ensuant   incident   nonessential   resultant   sequent