/ɡrəˈʧuːəti/ – Noun
Definition: tiền chè lá, tiền boa, tiền thưởng, tiền hối lộ, tiền đút lót.
A more thorough explanation: A gratuity is a sum of money given voluntarily or beyond obligation, typically as a reward or token of appreciation for services rendered.
Example: The employee received a generous gratuity from a satisfied customer for providing exceptional service.