unsubstantiatable

verb (used with object), sub·stan·ti·at·ed, sub·stan·ti·at·ing.

1. to establish by proof or competent evidence: to substantiate a charge.
2. to give substantial existence to: to substantiate an idea through action.
3. to affirm as having substance; give body to; strengthen: to substantiate a friendship.

verb (tr)

1. to establish as valid or genuine
2. to give form or real existence to

v.1650s, “to make real, to give substance to,” from Modern Latin substantiatus, past participle of substantiare, from Latin substantia (see substance). Meaning “to demonstrate or prove” is attested from 1803. Related: Substantiated; substantiating.