weariness of body or mind from strain, oppressive climate, etc.; lack of energy; listlessness; languor.

a condition of indolent indifference

the pleasant lassitude of the warm summer afternoon.

noun

apathy , dullness , exhaustion , fatigue , idleness , inaction , inactivity , languor , laziness , listlessness , sleepiness , sluggishness , tiredness , torpor , weakness , weariness , hebetude , languidness , leadenness , stupor , torpidity , disinterest , impassivity , incuriosity , incuriousness , indifference , insensibility , insensibleness , lethargy , phlegm , stolidity , stolidness , unconcern , uninterest , unresponsiveness , adynamia , blues , doldrums , drowsiness , enervation , ennui , hypokinesia