nonchalance (n.)

• acedia
• aloofness
• apathy
• ataraxia
• blah
• blahs
• carelessness
• casualness
• comatoseness
• detachment
• disinterest
• dispassion
• disregard
• dullness
• easygoingness
• heartlessness
• hebetude
• heedlessness
• hopelessness
• inattention
• indifference
• insouciance
• lethargy
• listlessness
• mindlessness
• negligence
• numbness
• passiveness
• passivity
• phlegm
• recklessness
• resignation
• sloth
• sluggishness
• sopor
• spiritlessness
• stupefaction
• stupor
• torpidity
• torpidness
• torpor
• unconcern
• unmindfulness
• withdrawnness