a mark against a person for misconduct or deficiency: If you receive four demerits during a term, you will be expelled from school.
the quality of being censurable or punishable; fault; culpability.
Obsolete. merit or desert.
Origin of demerit
1350–1400;Middle English (< Old Frenchdesmerite) < Medieval Latindēmeritum fault, noun use of neuter past participle of Latindēmerēre to earn, win the favor of (dē- taken in ML as privative, hence pejorative). See de-, merit
Related formsde·mer·i·to·ri·ous[dih-mer-i-tawr-ee-uh s, -tohr-]/dɪˌmɛr ɪˈtɔr i əs, -ˈtoʊr-/, adjectivede·mer·i·to·ri·ous·ly, adverb
late 14c., from Old French desmerite "blame, demerit" (Modern French démérite), from des- "not, opposite" (see dis-) + merite "merit" (see merit (n.)). Latin demereri meant "to merit, deserve," from de- in its completive sense. But Medieval Latin demeritum meant "fault." Both senses existed in the Middle French form of the word. Meaning "penalty point in school" is attested from 1862.