The Collaborative International Dictionary of English v.0.48:

Employee \Em`ploy*ee"\, n. [The Eng. form of employ['e].]
   One employed by another.
   [1913 Webster]

WordNet (r) 3.0 (2006):

employee
    n 1: a worker who is hired to perform a job [ant: employer]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "employee":
   assistant, blue-collar worker, breadwinner, casual, casual laborer,
   common laborer, day laborer, factory worker, flunky, free lance,
   free-lancer, full-time worker, girl Friday, hand, helper,
   hired hand, hired man, hireling, industrial worker, inferior,
   jobber, jobholder, junior, laborer, laboring man, man Friday,
   menial, mercenary, migrant, moiler, myrmidon, navvy,
   office temporary, pensioner, proletarian, right-hand man,
   roustabout, salaried worker, secondary, self-employed person,
   servant, stiff, subordinate, temporary, toiler, underling,
   understrapper, wage earner, wage slave, wageworker, worker,
   workgirl, workhand, working girl, workingman, workingwoman,
   workman



Bouvier's Law Dictionary, Revised 6th Ed (1856):

EMPLOYEE. One who is authorized to act for another; a mandatory.