From Scottish English, as past participle of preve, a Middle English variant of prove – compare woven (from weave) and cloven (from cleave), both of which feature -eve → -oven. preve died out in England, but survived in Scotland, where proven developed, initially in a legal context, as in “The jury ruled that the charges were not proven.” See usage notes for historical usage patterns.
Earlier, from Late Latin probō (“test, try, examine, approve, show to be good or fit, prove”, v), from probus (“good, worthy, excellent”), from Proto-Indo-European *pro-bhwo- (“being in front, prominent”), from Proto-Indo-European *pro-, *per- (“toward”) + Proto-Indo-European *bhu- (“to be”).
- Having been proved; having proved its value or truth.
- It's a proven fact that morphine is a more effective painkiller than acetaminophen is.
- Mass lexical comparison is not a proven method for demonstrating relationships between languages.
- (having been proved): unproven
Usage notes 
Historically, proved is the older form, while proven arose as a Scottish variant – see etymology. Used in legal writing from mid 17th century, it entered literary usage more slowly, only becoming significant in the 19th century, with the poet Alfred, Lord Tennyson among the earliest frequent users (presumably for reasons of meter). In the 19th century, proven was widely proscribed, and remained significantly less common through the mid 20th century (proved being used approximately four times as often), by the late 20th century it came to be used about equally.
- “prove” in The American Heritage® Dictionary of the English Language, Fourth Edition, Houghton Mifflin Company, 2000.
- “prove” in Merriam-Webster Online Dictionary, Merriam-Webster Online.
- “proved/proven”, Brians, Paul Common Errors in English Usage, (2nd Edition, November 17, 2008), William, James & Company, 304 pp., ISBN 978-1-59028207-6
- Third-person plural present indicative form of provar.
- second-person singular imperative of provir