implacableness

He earned his fame by the energy and implacableness of his hate.

But how, as I said in my former, could I sit down in quiet, when I knew how uneasy their implacableness made you?

Until middle life Mr. Cowen was as his father, immovable in principle; afterwards he was as his mother in implacableness.

She is very ill; the worse for some new instances of the implacableness of her relations.

Touch him there and out jumped jealousy, hate, and implacableness—and all the time one had been thinking of him as a kind of seer!