obligatory
Attendance at the safety briefing is obligatory for all new employees.
All new employees must attend the safety briefing; it is not optional.
Required by a legal, moral, or social rule; not optional.
It is obligatory to declare all goods at customs.
You are legally required to declare all goods at customs.
Often used in legal or formal administrative contexts to denote strict compliance.
Expected or required by social convention or custom.
A thank-you note is obligatory after receiving a gift.
Social norms dictate that you should send a thank-you note after receiving a gift.
Used to describe social expectations rather than legal mandates.
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Pro Tip
Formal vs. Informal
Use 'mandatory' or 'compulsory' for laws and rules. Use 'obligatory' for social duties or formal requirements. Avoid using it for casual suggestions.
Gold Rule
Not for Choices
Never use 'obligatory' to describe something you can choose to do or not do. If there is a choice, use 'optional'.
Word Origin
From Latin obligatorius, from obligare 'to bind', from ob- 'towards' + ligare 'to bind'.
Usage Notes
Use 'obligatory' when emphasizing that something is imposed by an external authority (law, rule, or strong social custom). It is more formal than 'required' and often implies a sense of duty.