The 'bushidan' that established the multilayer relationship from there became 'bushi' and the earlier steps from there was called as 'tsuwamono' and these became customarily used as academic terms.
そしてそこから「武士団」が重層的な関係を築く段階以降を「武士」と、そしてそれに至る前段階を「兵（つわもの）」と学術用語として定義したのである。