obligatory
adjectiveUK /əˈblɪɡ.ə.tər.i/
US /əˈblɪɡ.ə.tɔːr.i/
Something that you must do because it is a rule.
Wearing a helmet is obligatory when you ride a bike.
RELATED WORDS
OTHER MEANINGS
2. Expected because it always happens in a certain situation.
He gave the obligatory thank-you speech at the end.
3. Required by law or by an official rule.
It is obligatory to show your passport at the border.
4. Done or said only because it is the usual custom.
She added the obligatory joke to her presentation.