Snow Leopard does not mean anything. The Snow part of the name just means snow, and the Leopard part of the name means leopard. The difference between a regular Leopard and a Snow Leopard is that the Snow Leopard is white with black spots.
The direct ancestors of snow leopards were the other Asian leopards that live in the lowlands. It must have taken hundreds of generations for the leopards to fully adapt to the extreme conditions in which the snow leopards live today.