de ‧ mer ‧ it /diːˈmerət, diːˈmerɪt/ BrE AmE noun [countable]
1 . formal a bad quality or feature of something
demerit of
The merits and demerits (=the good and bad qualities) of this argument have been explored.
2 . American English a mark showing that a student has behaved badly at school ⇨ merit