A nanotale is a short story that consists of only six words. Some will say that it can be six words or less ... but personally, I like the strict definition, so I say six words or nothing. :-) No redefining the haiku for me ... :-)
The nanotale should fulfill one of two criteria, or ideally both:
1) It should tell a story
2) It should carry a double meaning
That is to say, a sentence may be constructed with six words that still says nothing to the reader beyond the information contained in those words. (I hope that makes sense. :-) A nanotale holds in its brevity both a beginning and an end beyond its literal content ... it starts the reader's imagination working and puts a story into their mind.
The creation of a nanotale is an attempt to reach beyond the literal.
Please bear in mind that these are my points of definition. I'm not looking to force my thoughts about this on you. But I hope it can pique your interest and get you to thinking ... and then, perhaps, to writing? :-)