Definition
Officially registered as an employee of a company or a member of an organization, society, sports team, etc.
在冊（受雇）
The software company currently has over five hundred employees on the books.
這家軟體公司目前有超過五百名員工在冊。
Our club currently has over two hundred members on the books.
我們的俱樂部目前有超過兩百名會員在冊。
Even though he hasn't played in a while, he is still on the books as a player for the team.
儘管他已經一段時間沒有上場比賽了，他仍然是球隊的註冊球員。