undeflectable

Jerome nose-down on the trail of a malefactor was almost as undeflectable as Father Ailnoth himself.

The Raven In The Foregate Peters, Ellis, 1913-1995 1986

For a moment the undeflectable star reporter was all chagrin.

No. 13 Washington Square Leroy Scott 1902

Whatever rigor this disciplining might cost you, a portion of the bread ration had to be left for the next morning's coffee, some of it indeed - by maintaining an undeflectable guard against the inclination of your every thought, and above all your itching fingers, to stray toward your pocket - for the lunch break: that way, and only that way, could you avoid, for instance, the tormenting thought that you had nothing to eat.

Imre Kertész - Prose 2002