From Middle English obligatorie, from Latin obligatōrius.

• (America) IPA: /əˈblɪɡətɔɹi/, /ˈɑblɪɡətɔɹi/
• (British) IPA: /əˈblɪɡət(ə)ɹi/

obligatory

1. Imposing obligation, legally, morally, or otherwise; binding; mandatory.

   an obligatory promise

   • 1673, Richard Baxter, Christian Directory:

     […] if he speak the words of an oath in a strange language, thinking they signify something else, or if he spake in his sleep, or deliration, or distraction, it is no oath, and so not obligatory.

2. Requiring a matter or obligation.

• bounden
• mandatory

• optional

• French: obligatoire
• German: obligatorisch
• Italian: obbligatorio
• Portuguese: obrigatório
• Russian: обяза́тельный
• Spanish: obligatorio