A contradiction between two beliefs or conclusions that are in themselves reasonable; a paradox.
Late 16th century (in the sense ‘a conflict between two laws’): from Latin antinomia, from Greek, from anti ‘against’ + nomos ‘law’.
“The trouble is the entire novel is an antinomy and so fails to be believable.”
Nothingburger (noun) (Chiefly US)
A person or thing of no importance, value, or substance. Now esp.: something which, contrary to expectations, turns out to be insignificant or unremarkable.
1950s: from nothing and burger. Added to the OED October 2018.