Why are snow leopards called ‘ounce’?
People want to know why snow leopards are called ‘ounce’. It is peculiar. An alternative to ‘ounce’ is ‘once’. They are both used interchangeably. We don’t know for sure the origin of this name.

Snow leopard Gobi Gurvan Saikhan NP Mongolia
It is thought to have originated in the Greek language. The Greeks used ‘lynx’ for all medium-sized cat species. Scientifically speaking this is not correct nowadays.
According to Ingo Rieger of Zurich Zoo in his work: “Some aspects of the history of ounce knowledge” published in International pedigree book of snow leopards 2: 1-36 1980..
“In Roman culture, the Greek term ‘lynx’ was Latinized to ‘lonza’, which was later transformed to the French ‘once’. Over the centuries the ‘l’ of ‘lonce’ was mistaken for an article (l’once) and thus the noun was reduced to ‘once’. From there the name was Latinized to ‘uncia’ and the snow leopard became Felis uncia.”
This explains the origin of the word ‘once’ but not ‘ounce’. However, I’d suggest that ‘ounce’ came about as an aberration or derivation from ‘once’ in usage over a long time which looks like ‘ounce’ missing the ‘u’. I have a feeling this was a question of pronunciation; people saying ‘once’ incorrectly by saying ‘ounce’.
I’d welcome corrections of you have time and superior knowledge.