OSU or OSS is one of the most well-known words in Kyokushin karate. It is used as a greeting, an expression of respect, agreement, readiness, and fighting spirit.

The word is believed to derive from the Japanese expression «oshi shinobu,» which can be translated as «to endure under pressure» or «to overcome hardship.» This is why OSU is so closely tied to the philosophy of Kyokushin.

In the dojo, the word OSU is used:
— when greeting;
— when responding to the sensei;
— before a bout;
— after training;
— as a sign of respect.

In Kyokushin, OSU symbolizes:
— discipline;
— respect;
— patience;
— the readiness to overcome hardship.

Many masters emphasize that the meaning of OSU goes far beyond a simple greeting. It is part of the philosophy of full-contact karate and the attitude toward training.