verb tr.1. To invoke as a witness. 2. To implore or beseech.
verb intr. 3. To protest. 4. To plead.
From Latin obtestari (to implore, affirm, protest), from ob- (on, over), from testari (to bear witness or to make a will), from testis (witness). Ultimately from the Indo-European root trei- (three), which is also the source of three, sitar, trivia (from trivium, place where three roads meet), trivial, troika, trivet, testimony, testament, attest, testify (to be the third person: to bear witness), triskaidekaphobia (fear of the number 13), tercel (the male of a hawk), and trammel (restraint, shackle, net). Earliest documented use: 1548.
“But I obtest, dear readers, I know nothing of any previous correspondence.”
Peter Hawes; Turakina Beach, Village of Thieves?; Manawatu Standard (New Zealand); Jul 8, 2008.