Novelette

A novelette is a complete story, told in (typically) fewer than 17,500 words.

As a literary form, this brevity is not to be despised: some notable novellas include...
 * The Fall of the House of Usher by Edgar Allan Poe
 * The Call Of Cthulhu by H.P. Lovecraft
 * The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson

Novelettes can be a difficult thing to sell, due to minimum price limits, but collections become a distinct possibility with this story form.