Meaning of RETAINER in English
[noun] [C] [specialized]A retainer is an amount of money which you pay to someone in advance so that they will work for you when you need them to.I pay my lawyer a retainer every month so that she's always available if I need her.(old use) A retainer is a servant who has usually been with the same family for a long time.
Cambridge English vocab. Кембриджский английский словарь. 2012