Made up, fabricated. Something which sounds true but has no basis in fact or
reality.
A casual
lie, or rash claim easily proven to be false by a simple
Google search. An ill informed claim might be said to be temious.
Etymology: From Latin temeritās (“chance, accident, rashness”) < temerē (“by chance, casually, rashly”).
His temious claims were believed by all but the more educated
among us.
While his statement sounded rational and to the point,
minor research proved them to be completely temious.