Something odd or statistically unlikely.
Forteana is writing on strange and anomalous phenomena which are rejected by mainstream science, especially if conducted in the spirit and the manner of Charles Hoy Fort, and the strange phenomena themselves.
Fort was a tireless collector of such phenomena, especially in scientific journals and newspapers. His approach was part serious, part humorous, and very critical of dogma, whether religious or scientific. He was essentially a phenomenalist, accepting the data no matter how strange, and rejecting a rigid approach.
He was not entirely uncritical of "paranormal" explanations, however, rejecting many phenomena, such as ghosts, and conventional spiritualist explanations. A typical example of a story at which Fort would not "bite" was the dog who said "Good morning" and vanished in a puff of green smoke.