vaniloquence

From Latin vanus (“vain”) + loquentia (“talk”).

vaniloquence (uncountable)

1. Idle or vain talk.
   • 1850, George Field, The analogy of logic, and logic of analogy‎, London: David Bogue, page 140:

     In philosophy, however, it is to be deplored that eloquence too commonly passes for science, being mistaken for logical acquirement; but truth alone is the just eloquence of philosophy, and without it the finest composition is, to the logician, but babbling and vaniloquence.

   • 2020, Ermanno Cavazzoni, translated by Jamie Richards, Brief Lives of Idiots, Cambridge, MA: Wakefield Press, page 12:

     Thus Pelagatti remained a loner throughout his life; he was frequently taken down to the police station, and subject to political identity crises that would plunge him either into obstinate silence or vaniloquence about the rocket engines and camels of the three wise men.