What a very good question.
Can not find a definition/etimology for the acronym VOLMET anywhere. Can not find it defined BUT:
ICAO Convention on International Civil Aviation, ANNEX 3 (Meteorology) Chapter 11 sections 11.4, 11.5, and 11.6 describe what is in a VOLMET and D VOLMET. Unfortunately, I am not a subscriber to this esoteric stuff, so only have the table of contents available online.
The World Meteorological Organization web site (
www. wmo.ch) defined a "D-VOLMET" as "Data Link Meteorological Information for Aircraft in Flight (VOLMET).
I would conclude, then, that:
a. a working definition of VOLMET is "Meteorological Information for Aircraft in Flight"
b. maybe it is only an acronym in a language other than English, likely French
c. it was likely snuck in somewhere by someone who spoke (egad!!) French. (duh)
d. france might be the place to look for the person that would do such a thing. (double duh, though don't overlook the Swiss or Belgium in the search)