semifable means that which is part fable and part truth. Lexicurio rates it Sui generis — a strength score of 89 out of 100.
Etymology
From semi- + fable.
noun
- That which is part fable and part truth.“1839, Thomas De Quincey, "William Wordsworth"", in Tait's Edinburgh Magazine
some snatches of tragical story , which , after all , might be an idle semi-fable, improved out of slight materials”