The Collaborative International Dictionary of English v.0.48:

Laborous \La"bor*ous\ (l[=a]"b[~e]r*[u^]s), a.
   Laborious. [Obs.] --Wyatt. -- La"bor*ous*ly, adv. [Obs.]
   --Sir T. Elyot.
   [1913 Webster]