unwieldy or clumsy because of weight and size
These two young creatures were the Honourable Mary and the Honourable Kate – scarcely appearing large enough as yet to bear the weight of such ponderous prefixes — Hardy
oppressively dull
ponderous prose
ponderosity /pondəʹrositi/ noun
ponderously adv
ponderousness noun
[Middle English via French from Latin ponderosus, from ponder-, pondus weight]