Adverb
in an essential manner
Source: WordNetI am never needlessly obscure-I am needfully obscure, when I am obscure. Donald Barthelme
This light is measured discreetly, needfully standing to us in the night. The light is cause of our life; the night is cause of our pain and of all our woe: in which we earn meed and thanks of God. Julian of Norwich
such expenses are necessarily incurred Source: Internet