free agency

Short definition from Wiktionary

Noun

1. 1
   A system through which professional athletes are free to play for or sign a contract to play for any team.
2. 2
   A system through which professional athletes are free to play for or sign a contract to play for any team: The movement of an athlete to a team through this system.
3. 3
   A system through which professional athletes are free to play for or sign a contract to play for any team: The status of an athlete as a free agent.
4. 4
   Synonym of free will