The Collaborative International Dictionary of English v.0.48:

Operose \Op"er*ose`\ a. [L. operosus, fr. opera pains, labor,
   opus, operis, work, labor.]
   Wrought with labor; requiring labor; hence, tedious;
   wearisome. "Operose proceeding." --Burke. "A very operose
   calculation." --De Quincey. -- Op"er*ose`ly, adv. --
   Op"er*ose`ness, n.
   [1913 Webster]