retainer
n. countablen. a fee you pay in advance to a professional, like a lawyer, to make sure they are available to work for you when you need them.
n. a preliminary fee paid to a professional, such as an attorney or consultant, to secure their services or ensure their future availability. Often refers to a recurring payment in a long-term service agreement.
The lawyer asked for a five-thousand-dollar retainer before starting the case.
The consulting firm remains on a monthly retainer to provide advice whenever the CEO requests it.
While some clients prefer hourly billing, others find that a fixed annual retainer offers more predictable costs and guarantees priority access to the firm's senior partners.
From retain + -er.
Often used with the preposition 'on' ('on retainer') to describe the state of being hired in advance.