in the Roman Catholic Church : a sin (such as murder) that will result in punishment that lasts forever unless the person who has sinned sincerely confesses to God and asks to be forgiven
What made you want to look up mortal sin? Please tell us where you read or heard it (including the quote, if possible).
Take our visual vocab quiz
A quick quiz about stuff worth knowing
The commonly misspelled words quiz
The Vocab Quiz Game for iPhone & iPad
"Incredibly fun and addictive. And informative!" User Review, iTunes