The Collaborative International Dictionary of English v.0.48:

Drudge \Drudge\ (dr[u^]j), v. i. [imp. & p. p. Drudged
   (dr[u^]jd); p. pr. & vb. n. Drudging.] [OE. druggen; prob
   not akin to E. drag, v. t., but fr. Celtic; cf. Ir. drugaire
   a slave or drudge.]
   To perform menial work; to labor in mean or unpleasant
   offices with toil and fatigue.
   [1913 Webster]

         He gradually rose in the estimation of the booksellers
         for whom he drudged.                     --Macaulay.
   [1913 Webster]