noun, masculine/ɑ̃.nɥi/plural: ennuis
ennui is masculine in French.
boredom; lassitude; trouble, issue, annoyance
“Notre ennui, nos mœurs fades sont le résultat du système politique.” — Our boredom, our insipid customs, are the result of the political system.
Inherited from Old French enui, probably from the verb enuier.