"completely unsubstantiated" is a correct and usable phrase in written English.
It means that a claim or statement has no supporting evidence or proof. Example: The politician's accusation against his opponent was completely unsubstantiated and caused a stir in the media.
At least, that's how his detractors see it; Daimler has dismissed the charges as "completely unsubstantiated".
They face trial and long prison sentences on bogus "security" charges that are completely unsubstantiated.
AMERICAN OFFICIAL SPEAKING ON THE CONDITION OF ANONYMITY "The claim of four children killed is completely unsubstantiated.
"Today, I'm hearing information that this is the day when something's supposed to happen — all completely unsubstantiated, but I've got a number of people chasing that down.
Mr. Clash, she added, "has not been convicted of a crime, but merely accused of one in a completely unsubstantiated, vague complaint".
"Someone will tweet, then retweet, and completely unsubstantiated things can proliferate so rapidly and destructively," Sunil's sister Sangeeta Tripathi said in an interview yesterday.
Steven Burkeman What a monstrous insult it is to print the totally unsubstantiated allegation that the Red Army carried out "rape on an industrial scale" (Letters, April 13), completely belittling the sacrifices made by the Soviet Union to destroy nazism (95% of all the fighting).
Brent Bryson, a lawyer representing Toney and the estate, dismissed the allegations as "completely ludicrous" and "unsubstantiated by any true facts".
The ministry said concerns over discrimination towards gay athletes at the games were "completely unfounded and unsubstantiated".
But what I think the American employment structure allows for is completely, let's say, unsubstantiated success.
"The idea that insurers conspired to limit claims is completely without merit and unsubstantiated," Mr. Hartwig said.
