/ɡrəˈtjuːɪtəs ˈprɒmɪs/ – Phrase
Definition: Lời hứa không phải là bắt buộc pháp lý.
A more thorough explanation: a promise that cannot be enforced as a contract because there has been no exchange of consideration (=the promise of payment or of something of value made in exchange for performance of a contract)
Example: This was simply a gratuitous promise, unenforceable in law.