| Samurai | 士 / 侍 | Warrior, "who serve in close attendance to the nobility". |  |
| San | 三 | three | |
| San | さ ん | polite suffix. Used between good friend, when attached to the first name. | |
| Sandan | 三 段 | Third degree black belt | |
| Sankyo | 三 教 | Third teaching. Basic technique with turning wrist | |
| Sankyu | 三 級 | 3. Kyu | |
| Sannin | 三 人 | three persons | |
| Satori | 悟 り | enlightenment ("understand") |  |
| Sayu | 左 右 | left-right | |
| Seiretsu | 整 列 | arrange in a row | |
| Seitaiho | 整 体 法 | exercises to correct your own posture |  |
| Seiza | 正 坐 | propper Japanese sitting (on knees) | |
| Sempai | 先 輩 | senior student | |
| Sen | 千 | one thousand | |
| Sen no sen | 先 の 先 | a defensive initiative launched simultaneously with the attack | |
| Senaka | 背 中 | back | |
| Sensei | 先 生 | born before, teacher, master | |
| Sensei ni rei | 先 生 に 礼 | bow to the teacher | |
| Sensen no sen | 先 先 の 先 | an initiative launched in anticipation of an attack where the opponent is fully committed to their attack | |
| Senshin | 先 心 | Purified Mind | |
| Shi | 四 | four | |
| Shichi | 七 | seven | |
| Shichikyu | 七 級 | 7. Kyu | |
| Shidoin | 指 導 員 | Instructor |  |
| Shihan | 師 範 | senior teacher, master instructor | |
| Shiho | 四 方 | four directions | |
| Shihonage | 四 方 投 げ | four directions throw | |
| Shikko | 膝 行 | Walking on the feet and knees while in the seiza posture | |
| Shin | 心 | Mind | |
| Shin | 身 | Body | |
| Shin Shin Toitsu Do | 心 身 統 一 道 | way of mind and body unification | |
| Shin-Shin-Toitsu | 心 身 統 一 | unification of mind and body | |
| Shin-Shin-Toitsu-Aikido | 心 身 統 一 合 氣 道 | aikido with mind and body unified | |
| Shinken | 心 剣 | sword of mind | |
| Shinshin | 心 身 | mind and body | |
| Shisei | 姿 勢 | Posture and attitude | |
| Sho | 初 | begin, first, new | |
| Shodan | 初 段 | First degree black belt | |
| Shoden | 初 伝 | first Ki Dan | |
| Shokyu | 初 級 | starting rank | |
| Shomenuchi | 正 面 打 ち | direct blow to the head | |
| Shoshin | 初 心 | Beginners Mind | |
| Sokushin | 息 心 | breathing with mind | |
| Sotaiho | 操 体 法 | method to affect the body of another person | |
| Soto | 外 | outside | |
| Suburi | 素 振 り | repetitive, individual, cutting exercises | |
| Sudori | 素 通 り | simply pass | |
| Sumo | 相 撲 | Japanese wrestling | |
| Suwari | 座 り | sitting | |
| Suwariwaza | 座 り 技 | technique while sitting | |