'bankroll' originates from English, formed from the compound 'bank' + 'roll', where 'bank' referred to a financial institution and 'roll' referred to a roll (bundle) of banknotes.

'bankroll' appeared in U.S. English in the mid-19th century as a noun meaning 'a roll of banknotes' or 'money kept for use'; by the late 19th and early 20th century it also acquired the verb sense 'to provide funds for'.

Initially it meant 'a roll of banknotes' (literal); over time the meaning broadened to 'funds available' and to the verb 'to provide funds for (someone or something)'.