adjective /ˈpɒn.dəɹ.əs,ˈpɑn.dɚ.əs/
[H]e saw, at the end of a shallow embrasure, a ponderous door of dark wood, braced with iron.
The great elephant, when the cage was being placed, would, at a signal from its keeper, place its ponderous head against one side of the cage and push.
Wikipedia foundation.