requisite

adj

1. Essential, indispensable, required.

   “Please submit the requisite papers before the end of the financial year.”

   “They ſay he is the King of Perſea. But if he dare attempt to ſtir your ſiege, Twere requiſite he ſhould be ten times more, For all fleſh quakes at your magnificence.”

   “[W]e endeavour to preſent our Gard'ners with a compleat Cycle of what is requiſite to be done throughout every Moneth of the Year: [...]”

   “On the other hand, there will be widespread agreement with Sir Brian's belief that, when a British main line has been completely dieselised and the schedules have been recast to suit the new traction, much higher daily mileages than 350 are not only possible but requisite, at least in the early stages of dieselisation.”

noun

1. An indispensable item; a requirement.

   “She had a good sort of coarse cleverness, admirably fitted to get on in the world; she possessed those two first requisites, a good constitution and a good temper;...”

   “But this something, what is it, unless the happiness of others, or some of the requisites of happiness?”

   “The main requisite is to brew a tasty, palateful and wholesome beer […]”