Nouns ending in -ment are masculine.
The suffix often marks an action or result derived from a verb.
Is mécontentement masculine or feminine?
lemécontentement
The rule behind it
99.6% of -ment nouns are masculine
In context
Ces règles alimentent le mécontentement parmi les étudiants.
Those rules foster discontent among students.
Les mouvements populaires expriment le mécontentement populaire.
Popular movements express popular displeasure.
C'est maintenant qu'est l'hiver de notre mécontentement.
Now is the winter of our discontent.