ponderous

Ponderous means heavy and slow — or dull and laboured. Movement, or prose.

The physical sense describes anything large moving without grace, so a ponderous machine or a ponderous animal. The writing sense is a real criticism, since ponderous prose is weighed down by its own seriousness and takes three sentences to arrive anywhere. The root is Latin pondus, a weight, which also gives ponder, meaning to weigh something up in your mind.