WordWeb Online

1. Difficult to handle or use especially because of size or weight
   "a cumbersome piece of machinery"
   - cumbrous
    
2. Not elegant or graceful in expression
   "his cumbersome writing style"
   - awkward, clumsy, inapt, inept, ill-chosen

See also: cumbersomeness, infelicitous, unmanageable, unwieldy