lourd

Ça pèse lourd.

It's heavy.

C'était lourd.

It was cumbersome.

Que tu es lourd !

How heavy you are!

Ce lit pèse lourd.

This bed is heavy.

Ce type est vraiment lourd, il arrête pas de me parler sans remarquer que je m’en fous.

This guy is really annoying, he won’t stop talking to me and doesn’t notice that I don’t give a shit.

C'est aussi lourd que du plomb.

It's as heavy as lead.

Lorsque je suis sorti, l'air était lourd.

As I stepped outside, the air felt clammy.

Lourd de conséquences

With far-reaching consequences, with serious consequences, that has significant implications (literally, “loaded with consequences”)

Ce livre est lourd.

This book is heavy.

J'ai un poids lourd.

I have a truck.

Le poids lourd traversa devant ma voiture.

The truck cut in front of my car.

Puis-je vous décharger du lourd paquet, Madame Meunier ?

Can I carry that heavy parcel for you, Ms Miller?