/əˈdəlt/ – Noun
Definition: người thành niên, người lớn.
A more thorough explanation: An adult is a person who has reached the age of majority, typically 18 years old or older, and is considered to be legally responsible for their actions.
Example: The legal age to purchase alcohol in this jurisdiction is 21, making it illegal for any ADULT under that age to buy or consume alcoholic beverages.