1. Laziness or indifference in religious matters or spiritual apathy or boredom in the practice of virtue: Every time Clifton had to attend church, a sense of acedia came over him; despite the fact that it has been personified as one of the deadly sins.
2. A mental syndrome, consisting of listlessness, carelessness, apathy, and melancholia (extreme depression): The patient was suffering from acedia which included indifference and a sluggish mental condition.
3. Etymology: from Late Latin, from Greek akedeia, indifference; a-, "no, not" + kedos, "care, concern".