straight grain, spindle tree, (kokuji)
柾 centers on straightness in wood: straight grain, and by extension the spindle tree, which is known for its straight-grained wood. It is a kokuji created in Japan.
柾 is a Japanese kokuji formed from 木 (tree) and 正 (correct, straight) to express the idea of straight-grained wood. The combination is semantically transparent.
A tree 木 that is correct and straight 正 produces straight grain. Picture a perfectly aligned log with grain lines running true.
For まさ, imagine a master carpenter named Masa inspecting the straight grain of a spindle tree plank: Masa -> まさ, and he nods at the perfectly straight grain.
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