dreadful; terrible

urgent; crucial

needing a lot of (mental or physical) effort

demanding

urgent; essential

necessary

of great influence or value

valuable, substantial

(of a person) making repeated and annoying requests

demanding, insistent

that cannot be satisfied

voracious, wanting

coming or happening at once; urgent; (of food, drink) that can be prepared quickly and easily

immediate, urgent

that must be; that cannot be avoided

essential

needing much effort

difficult; requiring hard labor

urgent; requiring immediate attention

important; urgent

causing tiredness, exhaustion, impatience etc

difficult, bothersome

important and so needing a quick decision or action; (of a person, voice etc) showing that something is urgent

needing immediate attention