Something necessary; an essential requisite.
Being such that it must exist, occur, or be true; essential; unavoidable.
Was it necessary, sir? – The Cattle-Baron's Daughter by Harold Bindloss
But it is necessary, first of all, that you trust me. – The Mystery of Metropolisville by Edward Eggleston
There's one point I didn't think necessary to tell your brother. – The Breaking Point by Mary Roberts Rinehart