The term 'unheard of' can be described by four crossword solutions: NOVEL (5 letters), EXOTIC (6 letters), bizarre (7 letters), and NEW (3 letters). A NOVEL is a long work of fiction, typically in book form, that tells a story. EXOTIC refers to something that is strikingly unusual or strange, especially in an interesting way. Bizarre means very strange or unusual, often so as to cause amusement or disbelief. Finally, NEW refers to something that has not existed before or that has been recently made, discovered, or created. All of these words together describe something that is unheard of, meaning it is completely unknown or unfamiliar.