A demerit refers to a fault or disadvantage associated with a person, object, or action. The term is often used formally to indicate a negative point or mark against someone’s record or a particular feature.
Demerits highlight shortcomings and are commonly referenced when evaluating or critiquing performance, behavior, or characteristics.
"The demerits of something or someone are their faults or disadvantages." — Collins Dictionary
This text explains that a “demerit” is essentially a mark of fault or weakness, used chiefly in formal contexts to indicate dissatisfaction or drawback.