"retainer" in the noun sense
1. retainer, consideration
a fee charged in advance to retain the services of someone
2. servant, retainer
a person working in the service of another (especially in the household)
a dental appliance that holds teeth (or a prosthesis) in position after orthodontic treatment
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License