Ōsu is a Japanese word that is often used in martial arts and other physical activities as a way of showing respect and acknowledging authority. It is similar to saying "yes, sir" or "yes, ma'am" in English.
When you say ōsu, you are typically bowing your head slightly and using a strong and confident tone of voice. This is a way of showing respect for your teacher, coach, or anyone else who is in a position of authority over you.
In addition to being a show of respect, ōsu can also be used to indicate agreement or understanding. For example, if your coach is explaining a new drill to you and asks if you understand, you might respond with a confident "ōsu" to let them know that you do.
Overall, the word ōsu is a way of showing respect, acknowledging authority, and indicating agreement or understanding in the context of physical activities like martial arts or sports.