Not mixed; pure:
Being without beginning or end:
The definition of endless is continuing forever, or lasting for a very long time.
Incapable of error; never wrong
A theoretical or experimental quantity, condition, or factor that does not vary in specified circumstances. Avogadro's number and Planck's constant are examples of constants.
That can be relied on; dependable; trustworthy
Named but not known or previously mentioned:
Happening over and over again; repeated often; going on in rapid succession
Going on or extending without interruption or break; unbroken; connected
That can be depended on; trustworthy; reliable
Never wearying; tireless:
The definition of staunch is someone or something strong, loyal or well made.
That cannot be doubted, questioned, or disputed; absolutely true; certain
In accordance with fact; that agrees with reality; not false
Worthy of trust; dependable; reliable
Free from error
Persistent or untiring.
Not permanent; not lasting; fleeting; temporary
Precarious; unstable; unreliable.
Conforming in every detail:
Continuing indefinitely, or during a long period; perpetual; sometimes used, colloquially, as a strong intensive.
The definition of incessant is continuing without stopping.
Without, or apparently without, end; lasting, or seeming to last, forever; endless
Made or done without stops:
Continuing indefinitely without interruption; unceasing; constant
The definition of relentless is persistent or unyielding.
Never slackening; persistent.
That cannot be tired out; not yielding to fatigue; untiring
That does not become tired; untiring or unwavering
Not tiring or ceasing; indefatigable or persistent:
Unrelenting or unremitting:
Bound to be successful or perform as expected:
Remaining continually unchanged
Existing or occurring without interruption or end
The definition of tired is being bored with something, or something that has become stale or being fatigued and in need of rest.
Find another word for unfailing. In this page you can discover 65 synonyms, antonyms, idiomatic expressions, and related words for unfailing, like: absolute, eternal, endless, infallible, constant, reliable, certain, failing, ongoing, ceaseless and continual.