untiring

Adjective

untiring (comparative more untiring, superlative most untiring)

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, [James Fenimore Cooper], chapter XVII, in The Last of the Mohicans; a Narrative of 1757. […], volume I, Philadelphia, Pa.: H[enry] C[harles] Carey & I[saac] Lea— […], →OCLC, page 278
   • He [Rev. John Knowles Montgomery] was a man of untiring energy and force of character, and accomplished what his predecessor could not do, as he introduced the Congregational form of church management.1916 February 15 (date delivered), W. W. Tasker, “Matthew Henry’s Chapel”, in Journal of the Chester and North Wales Archæological & Historic Society, volume XXII (New Series), Chester, Cheshire...

   Synonyms:

   indefatigable, inexhaustible, tireless, unflagging, unweariable, unwearying, weariless

2. (figuratively) Resolute, unfailing.
   • VVhat inexpreſſible ſenſation of delight does the ſoul at theſe moments conceive? Celeſtial bliſs! untiring, unabated rapture!1769, John Shebbeare, “The Different Sensations in the Human Breast, which Accompany What We Love, and What We Hate. Lady Flimsy’s Letter to Lady Liberal on that Subject.”, in Lydia, or Filial Piety....
   • So, with great perseverance and untiring industry, he prospered.1859, Charles Dickens, “Two Promises”, in A Tale of Two Cities, London: Chapman and Hall, […], →OCLC, book II (The Golden Thread), page 86

   Synonyms:

   tireless