The Collaborative International Dictionary of English v.0.48:

Toil \Toil\, v. i. [imp. & p. p. Toiled; p. pr. & vb. n.
   Toiling.] [OE. toilen to pull about, to toil; of uncertain
   origin; cf. OD. teulen, tuylen, to labor, till, or OF.
   tooillier, toailler, to wash, rub (cf. Towel); or perhaps
   ultimately from the same root as E. tug.]
   To exert strength with pain and fatigue of body or mind,
   especially of the body, with efforts of some continuance or
   duration; to labor; to work.
   [1913 Webster]