Part of Speech: Adjective

Definition: slow and clumsy because of dead weight or dull, laborious  or excessively solemn.

Source: Oxford Dictionary

Found in the 2nd line of ” Metaphors” by Sylvia Plath

This word was good to look up because the poem “Metaphors” is already an intense reading but the placement of the word “Ponderous”  is used to describe a house.