Requisite

Part of speech: noun (n.)

That which is required, or is necessary; something indispensable. God, on his part, has declared the requisites on ours; what we must do to obtain blessings, is the great business of us all to know. Wake.

Part of speech: adjective (a.)

Required by the nature of things, or by circumstances; All truth requisite for men to know. Milton.

Synonyms: Necessary; needful; indispensable; essential. Req"ui*site*ly, adv. Req"ui*site*ness, n.