ponderous
US /ˈpɑːn.dɚ.əs/
UK /ˈpɑːn.dɚ.əs/

1.
lourd, pesant, lent
slow and clumsy because of great weight
:
•
The elephant's movements were surprisingly graceful despite its ponderous size.
Les mouvements de l'éléphant étaient étonnamment gracieux malgré sa taille lourde.
•
The old machine made a ponderous noise as it started up.
La vieille machine fit un bruit lourd en démarrant.
2.
ennuyeux, lourd, solennel
dull, laborious, or excessively solemn
:
•
The speaker's ponderous delivery put half the audience to sleep.
La prestation lourde de l'orateur a endormi la moitié de l'auditoire.
•
He wrote a ponderous academic paper on the subject.
Il a écrit un article académique lourd sur le sujet.