plussage
/ˈplʌsɪdʒ/(also plusage) rare
noun
Something extra or added on; a surcharge; a bonus or increase to a salary or basic rate of pay.
Origin
1920s; earliest use found in The Mansfield News. From plus + -age. Compare Anglo-Norman and Old French plusage surplus, post-classical Latin plusagium surplus of expenditure over receipts.