retainer
noun [ C ] uk/rɪˈteɪ.nər/ us/rɪˈteɪ.nɚ/
law specialized聘用定金
an amount of money that you pay to someone so as to be sure that that person can work for you when you need them to
old-fashioned（服务多年的）仆人，佣人
a servant who has usually been with the same family for a long time
a faithful old retainer 忠实的老仆人