From Longman Dictionary of Contemporary Englishlassitudelas‧si‧tude /ˈlæsɪtjuːd $ ˈlæsətjuːd, -tuːd/ noun [uncountable] formal TIREDtiredness and lack of energy or interest SYN weariness
Examples from the Corpus
lassitude• The candidates have been trying to lift voters out of their lassitude.Origin lassitude (1400-1500) French Latin lassitudo, from lassus “tired” 