Tatami is already a Japanese word.
tatami
Tatami is a type of Japanese flooring made from rice,straw with a covering of woven soft rush straw.
"Tatami" in Japanese, is a japanese style flooring that is often used in Japanese homes and "dojo" (training hall). I am in karate so this is why I know some words in Japanese, plus I am taking lessons in the Japanese language.
In japan, mat is Tatami and we just call it Judo Tatami.
Japanese people use tatami mats as flooring in traditional rooms such as tea rooms and bedrooms. Tatami mats are also used for sitting and sleeping, as they provide a comfortable and natural surface. Additionally, tatami mats play a role in traditional Japanese customs and ceremonies.
Tatami.
Floor mats in traditional Japanese homes are called Tatami Mats.
Tatami.
Tatami mat
The matting is called a tatami and they are generally made from rice stalk straw.
The term Ryokan means a traditional Japanese inn or a small hotel. Since these are traditional Japanese inns, the guest living there had to sleep on the floor with their tatami prepared for them.