This is the 1567th most frequent French word.
obligatoire
Mandatory; required.
In this sentence, 'obligatoire' is used as an adjective meaning 'mandatory' or 'required' to indicate that wearing a helmet is not optional and is prescribed by regulations or necessity.
Porter un casque est obligatoire pour votre sécurité.
Wearing a helmet is mandatory for your safety.
Here, 'obligatoire' describes the compulsory nature of math courses, indicating they are essential and must be attended as part of the curriculum.
Les cours de mathématiques sont obligatoires jusqu'en secondaire.
Math courses are compulsory until high school.
In this case, 'obligatoire' emphasizes the requirement to register before a specific deadline, portraying a rule or obligation.