Mountain lions are known as..
The mountain lion has the most names of all the wild cat species. It is also known as the puma, cougar, panther, painter, catamount,
Theodore Roosevelt wrote in 1901:
“No American beast has been the subject of so much loose writing or of such wild fables as the cougar. Even its name is unsettled. In the Eastern States it is called panther or painter; in the Western states, mountain lion, or toward the South, Mexican lion. The Spanish speaking people call it simply lion. It is however sometimes called cougar in the West and South-west of the United States, and in South America, puma.”
The history of naming this cat is quite interesting. Columbus was one of the first to name this cat “lion”. This is because of its tawny coat which is similar to that of the African lion. This name is used throughout much of Spanish-speaking South and Central America. The name “puma” first appeared in 1609. The son of a Spanish conquistador said that the Indians called this cat “puma”.
As for the name “cougar” it appears to have been derived from a word used by German geographer, George Marcgrave in 1648 (“cuguacuara”). The French naturalist George Buffon called the cat “cuguar”.
The word “panther” is in fact a general word for a cat of uniform color and is often applied to the black leopard of Asia, “black panther”. However it is also used to describe the mountain lion notably for the Florida panther. The name was corrupted to “painter” in the southern United States. A shortened version of “cat-of-the-mountain” became catamount.
The name “puma” is used almost everywhere in South America. This version of the cat’s name is used mainly by scientists in North America whereas cougar and mountain lion are used by people in general in North America.
There is confusion as to whether we should capitalize the names. My understanding after years of reading about the wild cats is that we should not capitalize the names. For example: “puma” is correct while “Puma” is incorrect. We should capitalize the name of the country. For example: “Florida panther” and not “florida panther” and not “Florida Panther”.
On the internet there are widespread problems in using search engines because the sports companies and sporting teams use “puma” extensively and “cougar” describes a sexually permissive 50+ year old woman.
Source for name: Wild Cats of the World by the Sunquists. Buy the book.