Meanings of unbacked in English

He promises that this is no unbacked claim or a prediction, it is a spoiler.

Bravado that was clearly unbacked by real courage.

The simple statement, unbacked by any proof but the weight of Ralph's new authority, brought light and happiness.

His pride revolted at the idea of coming quite unbacked and disowned, as well as empty-handed, to Mr. Slocum.

How does a 20th-century mind process the relationship between esoteric, unbacked bitcoin and the dry goods people have always traded for?

The third paragraph starts out with an assertion unbacked by proof and the second sentence is a silly boast that no one believes.

He had yet to learn that treaty rights, unbacked by power, are worth little more than the paper upon which they are written.

Reliance upon high sounding words, unbacked by deeds, is proof of a mind that dwells only in the realm of shadow and of sham.

Honour is a fine bulwark against a small force; but, unbacked by other principle, it is seldom well manned enough to resist a large one.

Sir Lomer was playing the game of safety, when from his own temperament and position and unbacked by other leaders he could do little more.

The girl, publicly offered under unfavourable conditions, and unbacked by the auctioneer's laudatory harangues, could easily be knocked down for twenty aurei or even less.