Infalibly

Part of speech: adverb

Definitions

1. In a manner that is incapable of failing or making mistakes
2. executing with perfect reliability and certainty
3. characterized by an unwavering correctness in outcomes without error

Etymology: The Latin verb "fallere" meant "to deceive" or "to trip up," and it left English a surprisingly large family. "False" is its past participle, "fallacy" comes from the related noun "fallacia," and "fail" reached English through Old French "faillir." "Infallible" adds the negative prefix "in-" ("not") to "fallibilis," meaning "liable to err," so the core idea is something that cannot be tripped up or deceived. The adverb follows the same pattern, adding "-ly" to the adjective "infallible." The standard spelling has two l's, "infallibly," though the form in your request drops one. The adverb describes doing something in a way that cannot go wrong or be mistaken.

Synonyms: infallibly, certainly, unfailing, unerringly, assuredly

Antonyms: falsely, erroneously, mistakenly, uncertainly, doubtfully