Synonyms of unfailing in English:

unfailing


See US English definition of unfailing

See UK English definition of unfailing

See Spanish definition of indefectible

adjective

1‘he was remembered for his modesty and his unfailing good humour’

SYNONYMS
constant, reliable, dependable, steadfast, steady, sure
endless, undying, unfading, inexhaustible, boundless, ceaseless, never-failing, infallible
ANTONYMS

ephemeral, unreliable