1. Morally reprehensible, wrong or wicked; violating religious or moral law
   "they were expelled for sinful behaviour";
   - iniquitous, ungodly
    
2. Having committed unrighteous acts
   "a sinful person";
   - unholy, wicked
    
3. [informal] Very pleasurable and indulgent, especially regarding unhealthy food
   "A sinful chocolate dessert"

See also: epicurean, luxuriant, luxurious, luxury, sybaritic, unrighteous, voluptuary, voluptuous, wicked

Encyclopedia: Sinful