Quick Definition
Oss is a Japanese-rooted term used to show respect, acknowledge instruction, or express readiness and perseverance. Practitioners say it when bowing onto the mat, before and after training, or in place of a simple “yes.”
What is oss?
Oss, also written osu, is a greeting and acknowledgment used across several Japanese-rooted martial arts, most closely associated with Kyokushin karate and Brazilian jiu-jitsu. It has no single English translation. Depending on the moment, it can stand in for “yes,” “I understand,” “hello,” “goodbye,” or “I’m ready.”
The word exists because dojos run on an economy of language. A bow and one syllable can carry the weight of a full sentence without breaking the rhythm of a class.
Oss reached Brazilian jiu-jitsu through the sport’s roots in Japanese judo. Mitsuyo Maeda, the judoka who taught Carlos Gracie in the 1910s, carried Japanese training customs with him, and BJJ schools kept the word long after the sport diverged from those origins.
What separates oss from a plain “yes” is weight. Hai, the standard Japanese word for yes, is neutral by comparison. Oss carries more: it signals that the practitioner accepts the instruction and respects the person who gave it.
Where the word comes from
Martial artists have argued over the origin of oss for decades without settling on a single answer.
The most common theory ties oss to onegai shimasu, a formal Japanese request that roughly means “please, I’m in your care.” Through generations of daily use in the dojo, the phrase is believed to have worn down until only “osu” remained.
A second theory points to oshi shinobu, meaning “to push and endure.” This reading is what gives the word its kanji, 押忍, and its association with perseverance under pressure. The USA-IFK Kyokushin Karate association breaks the kanji down the same way: 押 (oshi, “to push”) and 忍 (shinobu, “to endure”).
A third, less common theory traces oss to a pre-World War II military or academic setting, possibly the Imperial Japanese Navy or a university sumo club.
Kyokushin karate, founded by Mas Oyama in the 1960s, built a philosophy around the word: osu no seishin, “the spirit of osu.” That branding is a big reason the term is so tightly linked to Kyokushin today, even though its use likely predates the style.
Oss vs. osu: is there a difference?
Oss and osu are the same Japanese word, just transliterated differently for English speakers. Neither spelling is more correct than the other.
| Spelling | Where it’s most common | Pronunciation note |
|---|---|---|
| Osu | International karate, especially Shotokan | Closer to the Japanese original |
| Oss | Brazilian jiu-jitsu and most English-speaking gyms | Final vowel dropped, rhymes with “boss” |
| Ossu | Some Kyokushin schools | Doubled consonant, sharper delivery |
The variation comes down to how faint the Japanese final “u” sound is in casual speech. Practitioners who learned the word from written karate terminology tend to write “osu,” while those who picked it up by ear in a BJJ gym tend to write “oss.”
How oss is used in training
The word does different work depending on when it’s said during a session.
Entering or leaving the mat: practitioners often bow and say oss as a greeting to the training space, a habit separate from greeting any particular person.
Acknowledging instruction: when a coach corrects a technique or gives direction, a quick oss confirms “understood” without breaking the flow of class.
Before and after sparring: training partners often exchange oss before rolling or sparring, and again afterward, regardless of who came out ahead.
Pushing through fatigue: some practitioners use oss mid-drill the way a lifter might grunt through a heavy set, as a way of gutting out effort rather than as a greeting.
Oss across karate, BJJ, and MMA
Oss carries different weight depending on the art. In Kyokushin karate, it’s close to mandatory: students bow and say it when entering the dojo, and instructors expect it as a response to nearly every direction.
In Brazilian jiu-jitsu, oss is common but looser, exchanged as a sign of respect between training partners rather than enforced the way a Kyokushin dojo enforces it.
Mixed martial arts sits somewhere in between, and the reason comes down to lineage. MMA gyms blend striking disciplines like Muay Thai and boxing, which never adopted oss, with grappling arts that did. A fighter who cross-trains heavily in BJJ is far more likely to say oss than one whose background is mostly wrestling or kickboxing.
When not to say oss
Oss is far from universal. Using it in the wrong setting can read as ignorance rather than respect.
Traditional Japanese dojos observe a strict sense of hierarchy, and oss is generally reserved for training-specific exchanges rather than casual conversation. Some instructors consider it out of place toward a senior outside that context.
Non-Japanese martial arts, including Muay Thai, boxing, and wrestling, don’t use the term at all, and saying it in one of those gyms can come across as borrowed slang rather than tradition.
Some karate schools have moved away from oss entirely, with instructors preferring the plain word hai on the grounds that genuine respect doesn’t need a specific loanword attached to it.
Frequently Asked Questions
Is it “oss” or “osu”?
Both spellings refer to the same word. Osu is more common in karate circles, oss in Brazilian jiu-jitsu, and neither is more correct than the other.
What does oss mean literally?
There’s no single literal translation. Depending on the theory, it comes from a shortened polite request (onegai shimasu) or from kanji meaning “push” and “endure” (oshi shinobu).
Do MMA fighters say oss?
Some do, particularly those with a strong jiu-jitsu background. Fighters who train mainly in striking arts like Muay Thai or boxing rarely use it.
Is it disrespectful to say oss?
Not in most BJJ or Kyokushin gyms, where it’s standard etiquette. In some traditional dojos, using it outside a training context or toward the wrong person can come across as inappropriate.
Why do BJJ gyms use a Japanese word?
Brazilian jiu-jitsu developed out of Japanese judo, brought to Brazil by Mitsuyo Maeda in the 1910s. Oss and several other Japanese terms carried over from that lineage.
Sources
- Wikipedia. “Oss (greeting).” Accessed September 2026.
https://en.wikipedia.org/wiki/Oss_(greeting) - USA-IFK Kyokushin Karate. “The Spirit of Osu.” Accessed September 2026.
https://uskyokushin.com/spirit-of-osu/ - Discover Discomfort. “What does “Oss” or “Osu” mean in Brazilian Jiu Jitsu?.” Accessed September 2026.
https://discoverdiscomfort.com/oss-osu-meaning-bjj-martial-arts/ - Kingz. “OSS BJJ: The Spirit of Respect, Discipline, and Drive.” Accessed September 2026.
https://www.kingz.com/blogs/news/oss-bjj - NAGA Fighter. “What does “OSS” mean?.” Accessed September 2026.
https://www.nagafighter.com/oss-meaning-bjj/ - The Martial Way. “The History of Osu! / Oss!.” Accessed September 2026.
https://the-martial-way.com/posts/history-of-osu-oss/ - Karate by Jesse. “The Meaning of “OSS” / “OSU”.” Accessed September 2026.
https://www.karatebyjesse.com/meaning-oss-osu-japanese/
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