Hi Derek,
DC> Nowadays there are many books, teachers and centers teaching
DC> vipassanaa. Of course, they use the word to designate a certain way
DC> of practicing. But how is the word vipassanaa used in the original
DC> sutta-s?
I use as definition
Anguttara Nikaya IV.94 Samadhi Sutta
http://www.accesstoinsight.org/canon/anguttara/an4-94.html
Not too detailed, but something for a start.
Metta,
Dimitry