Similar:
failproof,
foolproof,
infallible,
surefire,
failureproof,
certain,
sure-fire,
succeedable,
waterproof,
troubleproof,
more...
Opposite:
▸ Words similar to no-fail
▸ Usage examples for no-fail
▸ Idioms related to no-fail
▸ Wikipedia articles (New!)
▸ Words that often appear near no-fail
▸ Rhymes of no-fail
▸ Invented words related to no-fail