ab initio

adverb

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ab in·i·tio | \ ˌab-ə-ˈni-shē-ˌō

Definition of ab initio

: from the beginning

Starting Things With Ab Initio Example Sentences Learn More about ab initio

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Starting Things With Ab Initio

We'll tell you right from the beginning where ab initio comes from. This adverb was adopted at the beginning of the 17th century directly from Latin, where it translates as "from the beginning." (Initio is a form of the noun initium, meaning "beginning," which gave rise to such English words as initial, initiate, and initiative.) Ab initio most frequently appears in legal contexts, but it is not surprising to find it used outside of the courtroom. The phrase is also used as an adjective meaning "starting from or based on first principles" (as in "predicted from ab initio calculations").

Examples of ab initio in a Sentence

Recent Examples on the Web Moreover, the Executive Order exceeds the President’s authority and is therefore ultra vires and void ab initio. — Eriq Gardner, Billboard, "TikTok Employee Asks Federal Court to Immediately Stop Trump Order," 4 Sep. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ab initio.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.