Osu (押忍), often pronounced and written as “Oss” outside Japan, is commonly heard in karate and other Japanese martial arts. It can be used as a greeting, acknowledgement or response to an instructor.
However, osu is not simply the Japanese word for “yes”, nor is its use universal across karate.
Its meaning and appropriateness depend heavily on the tradition and culture of the dojo.
The precise origin of osu is debated, but its use is associated primarily with mainland Japanese male university, sporting and martial arts culture, rather than with the original Okinawan development of karate.
It became particularly prominent within the disciplined and hierarchical environment of Japanese university martial arts clubs during the twentieth century and subsequently became strongly associated with certain karate organisations.
One commonly repeated explanation is that osu developed as a shortened form of ohayō gozaimasu (おはようございます), meaning “good morning”.
Another explanation comes from the kanji commonly used to write it:
押 (osu) — to push or press
忍 (shinobu) — to endure, persevere or tolerate
This has led to the popular martial arts interpretation of “push and endure”, representing perseverance and determination.
Although this is a powerful martial arts philosophy, the kanji explanation is generally regarded as a later interpretation rather than a definitive explanation of the word's historical origin.
Not necessarily.
Outside the martial arts groups in which its use has become established, osu or ossu can be a very informal, masculine and somewhat rough expression in Japanese.
Historically, it has been associated particularly with male sporting clubs, university groups and other strongly hierarchical environments.
Because of this, using osu indiscriminately when speaking to somebody senior would not normally represent polite or formal Japanese.
Within a dojo where osu forms part of the established etiquette, however, it can certainly be intended and understood respectfully. The important distinction is that this meaning comes from the culture of that particular martial arts community, rather than osu itself being a formal Japanese expression of respect.
Karate developed in the Ryukyu Islands, principally Okinawa, before being introduced more widely to mainland Japan during the early twentieth century.
The widespread martial arts use of osu appears to have developed within mainland Japanese culture rather than the older Okinawan karate tradition.
This distinction is important because many practices now widely associated with karate developed after karate reached mainland Japan.
Consequently, hearing osu frequently in a modern karate dojo does not necessarily mean that it represents an ancient Okinawan karate custom.
Hai (はい) is the normal Japanese acknowledgement commonly translated as “yes”, although in many situations its meaning is closer to:
“Yes, I understand.”
“I have heard you.”
“Understood.”
When an instructor gives a command or correction, responding with hai therefore provides a clear and polite acknowledgement.
Unlike osu, it does not carry the same associations with informal male sporting or university culture.
For this reason, many traditional karate dojo use hai rather than osu when acknowledging instruction.
Although both may be heard as responses during karate training, they have different linguistic and cultural backgrounds.
| Hai (はい) | Osu / Oss (押忍) | |
|---|---|---|
| General meaning | Yes / understood / acknowledged | Informal acknowledgement or greeting |
| Normal Japanese usage | Yes | Limited / context dependent |
| Formality | Polite and widely appropriate | Traditionally informal and masculine |
| Historical association | Japanese language generally | Male university, sporting and martial arts culture |
| Okinawan karate origins | Consistent with normal acknowledgement | Not considered an original Okinawan karate convention |
| Martial arts usage | Acknowledging instruction | Greeting, acknowledgement, agreement or expression of spirit |
| Appropriate to senior instructors | Generally yes | Depends upon the tradition and relationship |
No.
In karate traditions where osu has become an established part of dojo etiquette, saying it is entirely normal. Within those traditions it can express respect, determination, acknowledgement and willingness to train.
The mistake is assuming that osu is universally traditional karate terminology, that it literally means “yes”, or that it is inherently a formal Japanese expression of respect.
It is better understood as a culturally specific expression adopted by particular Japanese martial arts communities and subsequently spread throughout much of international karate.
Using hai provides a simple and respectful acknowledgement of an instructor without relying upon the particular cultural conventions surrounding osu.
It also helps distinguish between the older roots of karate and practices that developed within mainland Japanese martial arts culture later in karate's history.
Neither expression should therefore be used simply because it “sounds Japanese”.
Understanding why a term is used is part of understanding the culture and history behind karate itself.