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,"
by Golden Girl February 17, 2015
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.
by Ville De Chaya May 28, 2009