unfailing

adjective

un·​fail·​ing ˌən-ˈfā-liŋ 

: not failing or liable to fail:

a

: constant, unflagging

unfailing courtesy

b

: everlasting, inexhaustible

a subject of unfailing interest

c

: infallible, sure

an unfailing test

unfailingly

ˌən-ˈfā-liŋ-lē 

adverb

Synonyms

• unerring
• reliable
• perfect
• flawless
• infallible

Examples of unfailing in a Sentence

She is known for her unfailing optimism.

an unfailing judge of personal character

Recent Examples on the Web

Yesterday’s pangrams were gainful, unfailing and unflagging. —Julia Jacobs, New York Times, 19 May 2025

She’s put off by his sweetness, his refusal to respond to her meanness and his unfailing encouragement, expressing pride in her tiniest recovery wins. —David Rooney, HollywoodReporter, 3 Sep. 2019

What is most important, always, is an unfailing loyalty to Trump. —Constance Grady, Vox, 25 Apr. 2025

Not just for the exceptional wines, but for these supremely authentic interactions that are born from an unfailing dedication to the land. —Nicole Kliest, Vogue, 29 Mar. 2025

Word History

First Known Use

14th century, in the meaning defined above

Rhymes for unfailing

• assailing
• availing
• bewailing
• blackmailing
• curtailing
• derailing
• descaling
• detailing
• dovetailing
• entailing
• exhaling
• impaling

Kids Definition

unfailing

adjective

un·​fail·​ing ˌən-ˈfā-liŋ 

ˈən-

1

: not likely to fail : constant, unflagging

unfailing support

2

: not likely to run out or be used up : everlasting, inexhaustible

an unfailing supply

3

: infallible sense 2

the unfailing mark of an amateur

unfailingly adverb