/tɜːrmɪˈneɪʃən ˈlɛtər/ – Phrase
Definition: Thư chấm dứt hợp đồng.
A more thorough explanation: a letter sent by one contracting party (=a person bound by a contract) to the other contracting party or parties, formally saying that it is ending the contract
Example: He had lawyers acting for him at the time and the termination letter was sent not only to him but his lawyers.