employ vs hireling

employ

noun
  • The state of being an employee; employment. 

verb
  • To hire (somebody for work or a job). 

  • To use (somebody for a job, or something for a task). 

  • To make busy. 

hireling

noun
  • An employee who is hired, often to perform unpleasant tasks with little independence. 

  • Someone who does a job purely for money, rather than out of interest in the work itself. 

  • A horse for hire. 

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