killing by inches; testing a sword's sharpness on a corpse
Historical term for a practice in the Edo period where a swordsman would test the sharpness of a blade by cutting a corpse, often a criminal's, in a series of cuts. Rarely used outside historical or literary contexts.
In the Edo period, killing by inches was carried out to test the sharpness of a sword.
From 五分 (gobu, 'half an inch') and 試し (dameshi, 'testing'), referring to the practice of making cuts at intervals of about half an inch on a body to test a sword's cutting ability.