testify

What it means

1. ambitransitiveTo make a declaration, or give evidence, under oath.

   One witness shall not testify against any person to cause him to die.

   1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Numbers 35:30

   2 more examples

   Michael Jackson probably died after he rapidly injected himself with a dose of the surgical anesthetic propofol on top of a large dose of sedatives he swallowed when Dr. Conrad Murray was away, the defense’s propofol expert testified Friday.

   2011 October 28, Alan Duke, “Michael Jackson gave himself fatal overdose, expert says”, in CNN, archived from the original on 29 Dec 2016

   It was only after a decade away from Skipton that I was finally able to garner the courage to return and testify against my abuser.

   2014 August 29, Ruzwana Bashir, “The untold story of how a culture of shame perpetuates abuse. I know, I was a victim”, in Alan Rusbridger, editor, The Guardian, London: Guardian News & Media, →ISSN, →OCLC, archived from the original on 09 Feb 2021

2. ambitransitiveTo make a statement based on personal knowledge or faith.

   We speak that we do know, and testify that we have seen; and ye receive not our witness.

   1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, John 3:11

   1 more example

   [T]he pleaſures of ſenſe have no reliſh vvhere thou [Jesus] irradiateſt and teſtifieſt vvith our conſcience, that vve are the children of God, and have done thy vvill ſincerely, […]

   1733, Tho[mas] Allen, “Jesus Christ’s Sixth Royal Embassy; or Word to the Angel of the Church in Philadelphia”, in The Christian’s Sure Guide to Eternal Glory: Or, Living Oracles Most Comfortable, Holy and Instructive of the Lord Jesus Christ from Heaven, in His Royal Embassy to the Seven Churches of Asia, […], London: […] Francis Jefferies […], →OCLC, page 253

3. ambitransitiveTo be evidence of.

   "Iberian-Sardinian" substrate features have been posited time and time again. These have usually been explained as testifying to a migration from the Iberian Peninsula to Sardinia in prehistoric times.

   2025, Cid Swanenvleugel, The Pre-Roman Elements of the Sardinian Lexicon, page 15

   1 more example

   Paradoxically, the sharp and unambiguous formulas in which Lenin called for the use of terror and denied the possibility of democracy and freedom testified to the fact that freedom had not yet been completely eradicated.

   1978 [1976], Leszek Kołakowski, translated by P[aul] S[teven] Falla, Main Currents of Marxism, volume II: The Golden Age, Oxford: Clarendon Press, translation of Główne nurty marksizmu: rozwój (in Polish), →ISBN, →OCLC, page 508

In a sentence

One witness shall not testify against any person to cause him to die.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Numbers 35:30

Where it comes from

1. Latintestificārī“to bear witness”
2. Old Frenchtestifier
3. Middle Englishtestifien
4. Englishtestify

PIE word *tréyes From Middle English testifien, borrowed from Old French testifier, from Latin testificārī (“to bear witness”), from testis (“a witness”) + facere (“to make”). See -fy.