>> Why not make a proper new word. Where would we be if we went around
>>talking about dorses rather than mules?
>Well, leaving aside that a 'dorse' would probably be a hinny rather
>than a mule....
>Creating a portmanteau is a longstanding way of making a proper new
>word. You probably even use them all the time.
Wow, that's a bit of pedantry that even I would have to be having a really bad day to engage in. Particularly given that only some of those are portmanteaus; they are, however, examples of what were, at one time, neologisms, although many of those are such no longer.
In any event, liger and tigon are attested going back to the 1930s, at least (and the actual animals -- ligers, in particular -- have been documented back to 1798). Besides, if you want to take a dip in that pool, have a look at Wikipedia's list of Panthera hybrids, which includes liligers, litigons, lileguars, jagopards, and many more. (Kind of mind-blowing how many of these hybrids are fertile, too, for that matter.)
"Mathematics brought rigor to economics. Unfortunately, it also brought mortis."
- Kenneth Boulding