lap dog vs retainer

lap dog

noun
  • A person who behaves in a servile manner, such as a sycophantic employee or a fawning lover. 

  • A small toy dog, kept as household pet, whose light weight and companionable temperament make it both suited and disposed to spend time resting in the comfort of its master's lap; a dog bred to behave in this manner. 

retainer

noun
  • A dependent or follower of someone of rank. 

  • A fee one pays to reserve the other's time for services. 

  • A device that holds teeth in position after orthodontic treatment. 

  • Any thing or person that retains. 

  • A retaining valve. 

  • A paid servant, especially one who has been employed for many years. 

How often have the words lap dog and retainer occurred in a corpus of books? (source: Google Ngram Viewer )