noun (frequently plural) an expense not budgeted or not specified.
— synonyms: incidental_expense, minor_expense
noun an item that is incidental.
adjective (sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence.
— synonyms: incident
adjective not of prime or central importance.
— synonyms: nonessential, accidental
adjective occurring with or following as a consequence.
— synonyms: attendant, consequent, accompanying, concomitant, ensuant, resultant, sequent, collateral
Examples
“She's costing us a lot in incidentals.”
“That character, though colorful, is incidental to the overall plot.”