Hi Anna,
Thank you for your reply! A complete definition can help me to improve my "long exposure" photographies ;-). For me a long exposure photography have something special that I can't explain...the little thing I missing to make a good photo of long exposure! For these reason I like to have the definition of many photographers for long exposure.
If you look this picture : http://1x.com/photo/160471/all:user:132828, it is a long exposure photography if I take your definition because motion is visible, and the time exposure is something like 1/10. And I agree that it is a long exposure photography srticto sensus. But for me (it is a personal feeling), this picture is far from the "Long exposure" spirit...
For me a long exposure photography should be peaceful. But I already see a long exposure of a storm! That was amazing but not peaceful at all and a really good long exposure photography.
Moreover, when I look at the section "Action" in 1X photos, I can see motion in almost 80% of photographies. But it is not long exposure photographies.
Maybe my English is too poor to convey my feelings...
Anyway, I am happy to discuss the definition of a long exposure with photographers interested in this kind of photography to understand their feelings! But you are right: maybe I should ask what are your feelings when you think about long-exposure photography? :-)