undeadliness

Undead --- I looked up the term 'undead' in the dictionary, and found that words like 'undeadly' and undeadliness 'were obsolete terms for immortal and immortality.

So You're Thinking of Writing a Vampire Novel.... nissa_amas_katoj 2009

For as man is a mingled thing of two substances, a bodily and a ghostly, so it needeth for to have two sere [225] means to come by to perfection; [226] sith it so is that both these substances shall be oned in undeadliness at the uprising in the last day; so that either substance be raised to perfection in this life, by a mean accordant thereto.

The Cell of Self-Knowledge : seven early English mystical treatises printed by Henry Pepwell in 1521 Henry Pepwell 1902

But to meet God! And 'tis no sweven, [dream] ne fallacy, this dread undeadliness [immortality] -- it is real.

The White Rose of Langley A Story of the Olden Time Emily Sarah Holt 1864

He that dwelleth between the terms hath nearhand forsaken deadliness, but not fully, and hath nearhand gotten undeadliness, but not fully; for whiles that him needeth the goods of this world, as meat and drink and clothing, as it falleth to each man that liveth, yet his one foot is in this deadly life; and for great abundance of ghostly joy and sweetness that he feeleth in God, not seldom but oft, he hath his other foot in the undeadly life.

The Cell of Self-Knowledge : seven early English mystical treatises printed by Henry Pepwell in 1521 Henry Pepwell 1902

‘undeadliness’ for immortality; ‘uncunningness’ for ignorance;

English Past and Present Richard Chenevix Trench 1846