I gave you a perfectly concise definition of massicity, I assure you it's not a spelling error, I have employed the term on this site since I can remember, as have others.
Well I used the famous FES 'Search' function. You are right, others have used the word - I am one of them, questioning it's validity. But you know what, there is only one page of the search results for "massice" and
you are the only person to use it initially in any discussion. It won't take you or anyone else long to confirm what I have found.
Since I am neither an etymologist nor a lexographer, I cannot explicate its origin or why it is not in your dictionary. Bear in mind, a lot of dictionaries do not include the vast number of scientific field-specific terms which exist, since there are millions of them in different fields. Only somebody discussing electrostatic repulsion would ever have cause to use the word "massice", so perhaps it has been omitted from a number of lay-dictionaries. As far as I know it is an accepted term.
I have searched Google for "massice" - no hits.
I have also searched
http://dictionary.reference.com/ for "massice" - no hits.
I have searched Google for "electrostatic repulsion" and gone through the first page of topics and found the word twice. However, when checking further the word has been changed to massive.
You can do all of these searches yourself as can any other member on here but I'm certainly not going to do any more trawling through web pages that come up on the Google search. Alternatively, what
you could do is just post up your reference for your definition of the word "massice". I'm sure it's not too difficult a job, you must have got it from somewhere.
*Edit* I've just searched 'New Scientist' http://www.newscientist.com/search?doSearch=true&query=Massice
Yep, you guessed it:
Sorry, there were no results that matched your search.
*edit* Same result at
Nature.com