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.