1. required by law, rule, or custom; mandatory
2. so customary or expected as to seem required
Usage: often used to describe predictable social conventions

Examples

• Wearing a helmet is obligatory when riding a motorcycle.
• Military service is obligatory in some countries.
• The meeting includes the obligatory introductions and small talk.
• Safety training is obligatory for all new employees.
• He made the obligatory thank-you speech at the end of the ceremony.
• Attendance at the orientation session is obligatory for freshmen.
• The film had all the obligatory chase scenes and explosions.