As yet he could not reveal his unsubstantiated information to another.
He conscientiously avoids the vague, the doubtful, the unsubstantiated.
The articles seemed woven of fact, but she could not accept them unsubstantiated.
But he couldn't prove it, and she wasn't likely to accept his unsubstantiated word.
Then follows the unsubstantiated story which has done duty for Shakspeare ...