Infallible (adjective) — معصوم من الخطأ: Incapable of making mistakes or being wrong. Below are 8 words with a similar meaning; the linked ones have full GL Dictionary entries with their meaning in Arabic.
Consistently good in quality or performance; able to be trusted.
So well designed that it cannot fail or be misused.
Sure; definite; free from doubt — known with confidence after evidence, not guesswork; an adjective of certainty, not the noun ceremony and not the verb certify
unerringfaultlessperfectflawlessunfailing