The Japanese word for "Lion" is raion ライオン, a katakanization.
Another word for "Lion" is shishi 獅子.
- raion is the normal Japanese word for lion, while shishi is what the Chinese called the animal they had heard about in legends. Before knowing what a lion actually was, they had an idea of how a lion looked like from stories. So when they met animals that fit the description of a lion, they assumed they were lions, shishi, even when they weren't. Which is why shishi can refer to some things that aren't lions.
Scientific name: Panthera leo.
Beware: some kanji that are difficult to handwrite are easy to type on the computer, which may skew the usage statistics.