ponderous in WordNet English dictionary

1. slow and laborious because of weight
   "the heavy tread of tired troops"; "moved with a lumbering sag-bellied trot"; "ponderous prehistoric beasts"; "a ponderous yawn"
   heavy  lumbering  ponderous 
   
2. having great mass and weight and unwieldiness
   "a ponderous stone"; "a ponderous burden"; "ponderous weapons"
   ponderous 
   
3. labored and dull
   "a ponderous speech"
   ponderous