The Jaberwock is the most obscure of beasts, perhaps not quite as impossible as the Snark, which is of course beyond any description, any observer quite vanishing away before they can relay either an accurate or approximate description of that nonsenses appearance.
Lewis Carrol, or Master Charles Lutwidge Dodgson, as he was better known at the time, created the terrible image of the Jabberwock for a most improbable tale, published in his own adolescent magazine for the amusement and probably consternation of relatives and friends. The work was a most unlikely and almost indecipherable piece of rhyming prose, penned as complete gobbledygook, using words picked haphazardly from out of the air without reference to any known language spoken or written.
The compete poem reappears in ‘Through the Looking Glass’ first published under the pen of the now adult Lewis Caroll in 1871. The heroine of the piece, Alice, finds a most mysterious book whilst in the company of the White King and Queen, that proves to be impossible to read in any sensible way. With her usual quick mind Alice realizes that the book is printed in mirror writing, reflecting exactly the construct of looking glass world, and holding the volume up to a hand mirror is able to read if not understand the strange stanzas. A little later in the text Humpty Dumpty, a most unfortunate ovoid, translates some of the more obtuse words and phrases for Alice’s elucidation, although the use words like beamish, gyre, gimble, or mimsy, might serve Alice in her future endeavors is somewhat open to question.
The Jaberwock proves to be a most unpleasant creature, perhaps somewhat reminiscent of a griffin, with according to the illustrator John Tenniel the leathery wings of a tetradactyl and the long scaly neck and tail of a sauropod, no doubt a homage to the Victorian obsession with pseudo-science, paleontology, and geology.
That the wholly imaginary beast remains an iconic representation of knee knocking terror has much to do with that lack of detail. Mythical creatures hold a most firm grip on the imagination, particularly in childhood.