WordNet sense 1 (a disinclination to work or exert yourself):

slothfulness

WordNet sense 2 (any of several slow-moving arboreal mammals of South America and Central America; they hang from branches back downward and feed on leaves and fruits):

tree sloth

WordNet sense 3 (apathy and inactivity in the practice of virtue (personified as one of the deadly sins)):

laziness, acedia, acedia