The Collaborative International Dictionary of English v.0.48:

Hireling \Hire"ling\, a.
   Serving for hire or wages; venal; mercenary. "Hireling
   mourners." --Dryden.
   [1913 Webster] Hire purchase agreement
   Hire purchase

The Collaborative International Dictionary of English v.0.48:

Hireling \Hire"ling\ (h[imac]r"l[i^]ng), n. [AS. h[=y]reling.
   See Hire, n., and -ling.]
   One who is hired, or who serves for wages; esp., one whose
   motive and interest in serving another are wholly gainful; a
   mercenary. "Lewd hirelings." --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hireling
    n 1: a person who works only for money [syn: hireling,
         pensionary]