Substantiate, v. t. [imp. & p. p. Substantiated; p. pr. & vb. n. Substantiating.]
1. To make to exist; to make real. Ayliffe.
2. To establish the existence or truth of by proof or competent evidence; to verify; as, to substantiate a charge or allegation; to substantiate a declaration. Observation is, in turn, wanted to direct and substantiate the course of experiment. Coleridge.
Shades of meaning
Fernald has no entry of its own for substantiate; he lists it under confirm.
He lists it without comment; the entries above explain its neighbors.