What is lassitude?

The drowsy state that one achieves after eating a large meal at an Indian restaurant.

Thank you for dinner Anoop. Such mango lassitude I have, I could schluff off right here.

lassitude - meme gif

A total and completly lack of energy, a state of physical or mental weariness.

I was so overcome with lassitude that I couldn't get out of bed.
"Mum I won't be getting out of bed today, I'm overcome with lassitude,"