SINFUL Meaning of SINFUL in English [sin.ful] adj (bef. 12c) 1: tainted with, marked by, or full of sin: wicked 2: such as to make one feel guilty "a ~ chocolate cake" -- sin.ful.ly adv -- sin.ful.ness n Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012