free agent
noun
1- a person who does not have any commitments that restrict their actions行动自由的人（指对他人不承担任何责任, 因而行动不受制约的人）。
1.1
- a sports player who is not bound by a contract and so is eligible to join any team自由人（不受合同约束, 可参加任何运动队的运动员）。