1. Something that is necessary, urgent, or unavoidable; something that must be done
It is imperative that we act quickly.
É imperativo que ajamos rapidamente.
2. (Grammar) The mood or form of a verb that expresses commands or requests
In English, 'Go!' is the imperative form.
Em português, 'Vai!' é a forma imperativa.
3. A principle or rule that must be followed; a moral or ethical requirement
Honesty is a categorical imperative in business.
A honestidade é um imperativo categórico nos negócios.