No-trade clause

From BR Bullpen

A no-trade clause is a feature in a player's contract that limits his team's ability to trade him to another team. A no-trade clause can be comprehensive, covering all teams, or limited, including only a set number of teams designated by the player. The clause can be more or less strict; in stricter cases, a player will simply veto a trade to which he does not agree, while in a less strict one, his club will pay him compensation to have him waive the clause.