A duty, obligation, or responsibility — something one is required or expected to do (often legally or morally).
納税は国民の義務だ。
Paying taxes is a citizen's duty.
会社員としての義務を果たすことが重要だ。
It's important to fulfill your obligations as a company employee.
契約上の義務を怠ると、損害賠償が請求されることがある。
If you neglect contractual obligations, you may be liable for damages.