obligatory sign
nounUK /əˈblɪɡ.ə.tər.i saɪn/
US /əˈblɪɡ.ə.tɔːr.i saɪn/
A sign that tells you something you must do.
The obligatory sign at the pool says you must take a shower before swimming.
RELATED WORDS
OTHER MEANINGS
2. A traffic sign that shows a rule drivers must follow.
The blue obligatory sign means you must turn left here.
3. A symbol in a game or test that marks something you have to do.
Look for the obligatory sign on the map to find your next task.
4. A notice that something is required by law.
The obligatory sign on the door reminds workers to wear helmets.