to cut, a stump
柮 centers on the act of cutting or the result of cutting: a stump. The two meanings connect through the idea of severing or truncating something, leaving a cut end.
柮 combines 木 (tree/wood) with 出 (exit/come out), but the exact historical development is uncertain. It may have originally depicted cutting wood or a stump emerging from the ground.
A tree 木 with something sticking out 出: imagine cutting off the protruding part, leaving a stump.
For トツ, picture a tots (a made-up sound like a sharp cut) as the axe hits the stump: tots -> トツ.
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