zwingend
Translation
mandatory, compelling, essential, imperative
Examples
Das ist ein zwingender Grund.
That is a compelling reason.
Eine Anmeldung ist zwingend erforderlich.
Registration is mandatory.
Grammar Patterns
as an adjective modifying a noun a compelling proof
as an adverb modifying an adjective sth. is absolutely necessary
Similar Words
Synonyms: obligatorisch, notwendig; Antonyms: freiwillig, optional
Etymology
It's the present participle of 'zwingen' (to force, compel), so it literally means 'forcing' or 'compelling'.
Memory Tips
The sound 'zwing' can remind you of a strong, forceful action, like something mandatory.