I actually have sitting right in front of me an article titled "Mink
Breeding & Color Phases".  It was printed in the Blue Book of Fur Farming
in 1992.
 
It says "An example of additive gene expression is the gigas mink, in which
multiple genes act together to produce a large body size."  Seeing that
Douig McKay also breeds mink, I can see that he called his "giant" ferret
Gigas.
 
Lets look at the two words - "Demi" and "Gigas".
 
From an on-line dictionary
(http://www.dictionary.com/cgi-bin/dict.pl?term=demi):
demi- \Dem"i-\ [F. demi-, fr.  L. dimidius half; di- = dis- + medius
middle.  See Medium, and cf.  Demy, Dimidiate.] A prefix, signifying half.
 
From a Latin on-lin dictionary
(http://lysy2.archives.nd.edu/cgi-bin/words.exe?gigas):
Gigas - giant; Giant; the Giants (pl.); (race defeated by the Olympians)
 
So what does "Demi Gigas" means?  Half a giant?
[Posted in FML issue 3327]