Formal:
* Mandatory: This is a strong synonym, emphasizing that something is required.
* Compulsory: Similar to mandatory, suggesting something is enforced by law or rules.
* Required: This is a more neutral synonym, simply stating that something is necessary.
* Essential: This emphasizes the importance of something, often suggesting it is crucial for a successful outcome.
* Indispensable: This emphasizes that something is absolutely necessary and cannot be done without.
Informal:
* Must-do: This is a casual way of saying something is required.
* Necessary: This is a simple and straightforward synonym.
* Expected: This suggests that something is anticipated and therefore required.
* Customary: This emphasizes that something is traditionally done.
* Routine: This suggests something is done regularly and therefore expected.
The best synonym will depend on the specific situation and the tone you wish to convey.
