imperativeness

adjective

1. having the nature of, or indicating, power or authority; commanding: an imperative gesture
2. absolutely necessary; urgent; compelling: it is imperative that I go
3. Gram. designating or of the mood of a verb that expresses a command, strong request, or exhortation

noun

1. a binding or compelling rule, duty, requirement, etc.
2. a command; order
3. Gram.
   1. the imperative mood
   2. a verb in this mood