Carelessness, heedlessness, indifference, or casual unconcern.
Nonchalance.
Listless indolence or inactivity, especially if enjoyable or relaxing; dreaminess; (countable) an instance of this.
A state of the body or mind caused by exhaustion or disease and characterized by a languid or weary feeling; lassitude; (countable) an instance of this.
Dullness, sluggishness; lack of vigour; stagnation.
Heavy humidity and stillness of the air.
Melancholy caused by lovesickness, sadness, etc.; (countable) an instance of this.
To languish.