untiring

adjective2

1. •
   Not able to be tired; inexhaustible, tireless.

   • Alice had dropped senseless on the earth, and Cora had sunk at her side, hovering, in untiring tenderness, over her lifeless form. — 1826
2. •
   (figurative) Resolute, unfailing.

   • VVhat inexpressible sensation of delight does the soul at these moments conceive? Celestial bliss! untiring, unabated rapture! — 1769