training, (kokuji)
躾 centers on disciplined training, especially the cultivation of proper behavior and manners. It is a Japanese-made kokuji character.
躾 is a Japanese kokuji formed by combining 身 (body) and 美 (beauty), suggesting the cultivation of beautiful bodily conduct through training.
The body 身 is made beautiful 美 through disciplined training. Picture a person practicing proper posture and manners until their body reflects beauty.
For しつ, imagine a strict training session where the instructor says 'shh, it's discipline time': shh-itsu -> しつ, tying the sound to the idea of quiet, focused training.
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