ponderous
Definitions
Slow and clumsy because of great weight.
Dull, laborious, or excessively solemn.
Examples
The professor spoke in a ponderous tone that made the lecture feel much longer than it actually was.
The elephant moved with a ponderous gait, shaking the ground with every heavy step.
He struggled to finish the ponderous novel, which was filled with overly complex sentences and dense philosophical arguments.