Ignotum per ignotius
Ignotum per ignotius (Latin for "the unknown by the more unknown") refers to an explanation more unfamiliar than the concept which it seeks to explain.
An example would be: "The oven felt hot because of Fourier's Law." It is unlikely that a person unfamiliar with the hotness of ovens would be illuminated by a reference to the fundamental laws of physics. Of course, such a person might exist in theory, so ignotum per ignotius is not strictly a logical fallacy; it is just a criticism of an argument on rhetorical grounds, stating that such an argument is not useful in a particular context.
Ignotum per æque ignotum
Ignotum per æque ignotum, meaning "the unknown by the equally unknown", is a related form of fallacy in which one attempts to prove something unknown by deducing it from something else which is also not known to be true.