Oss is a phonetic expression, formed in Kanji out of two characters. The first Osu means to push or control and determines the pronunciation of the whole term. The second character shinobu (in Kanji) has the literal meaning to bear, endure or suffer. It is a generic term taken from Japanese martial arts but was created in the Japanese Navy. It is generally understood to be taken as an enthusiastic yes or to simply acknowledge someone as when bowing.
The first definition of Oss as an abbreviation for Onegai Shimasu, which translates into a request, a solicitation, an invitation like “please”, “if you may” or “with your permission”, much used as when inviting a partner to train. The second definition of the word, also known as Osu, means Oshi Shinobu, which conveys the idea of “persevering when pushed”. In other words, never give up, have determination, grit, spirit and withstand the most arduous of training. Carrying on without giving up, under all kinds of pressure – that’s the idea of inner strength so common in Asian culture. Therefore, at the start of a fight, the martial artist will shout or emanate the Oss, as a way of letting this sentiment out.
In many sources, the term is defined as a manifestation of ki energy, or in other words, a different kiai (strength), indicating one is ready to fight. According to Miyamoto Musashi, in the book “Go rin no sho” (Book of the Five Rings), the samurai would use three types of shouts: one before combat, the second during combat, when attacking, to muster greater strength (kiai), and the third after the fight, to celebrate victory or bemoan defeat. Oss beyond demonstrating strong spirit and determination before a fight, is also used to suggest or confirm a piece of information. Thus, whenever a Sensei asks or informs of something, the response is Oss. It is the response that will signify understanding or confirm understanding and that one will endeavor to try ones hardest both in spirit and to perform the move or technique to the best of one’s ability. In western dojo it now may be taken to mean a whole manner of interpretations depending upon the intonation of the speaker’s voice.
Before and after training the class simultaneously bow to sensei and say Oss! as a salutation, greeting and mark of respect, similarly at the end of a session as a mark of gratitude for the class. Oss should never be said quietly nor with just using the vocal cords alone. It should be spoken in a more gutteral way, from the Hara. It is just one way of displaying one’s spirit and respect.