What does a flat-headed nail mean?

This word means that a person or thing has always maintained integrity and honesty without any hypocrisy or change.

This word describes the frankness, truthfulness and credibility of such a person or thing, and it is often used to describe a person's quality, especially those who always keep truthfulness, truthfulness and honesty in words and deeds.

The word "flat head" means no inclination, no bulge, like still water; "Jiazi" means sixty years old, and can also be used to refer to sixty. Therefore, "flat-headed jiazi" can be used to describe a person who is over 60 years old and has always maintained integrity and honesty.