The Vietnamese word "mỗ" is an informal term often used to refer to someone whose name is unknown or forgotten. It can be used similarly to the English phrase "what's-his-name" or "what's-her-name." It’s a way to indicate that you can’t recall a person's name but still want to reference them in conversation.
Mẹ mỗ đây là con nhà gia giáo.
(This is the child from a good family, what’s-his-name.)
Ông mỗ ở xã mỗ.
(That guy lives in what's-its-name village.)
In more advanced usage, "mỗ" can also refer to a person whose identity is purposely kept vague, such as in storytelling or when discussing someone in a humorous or light-hearted context.
The word "mỗ" is a handy term in Vietnamese to refer to someone whose name you can't remember or don't know. It's informal and best suited for casual conversations.