1. The meaning of "Zi"
Ancient honorific: In ancient times, "Zi" was often used as an honorific for those who were moral, knowledgeable or noble. Such as Confucius, Laozi, etc. The "Zi" here is not their real name or character, but the honorific title given to them by later generations.
A general term for adult men: In ancient Chinese, "子" was sometimes used as a general term for adult men, similar to the modern "Mr." or "Jun".
Other meanings: "子" has many meanings in Chinese, such as referring to children (now specifically referring to sons), fruits of plants, eggs of animals, young or small objects, and the third of the earthly branches. One waits. But these meanings have nothing to do with the "zi" in the names of ancient sages.
2. The real names and names of ancient sages
Confucius: named Qiu, courtesy name Zhongni, a native of Zouyi (now Qufu, Shandong) in the state of Lu in the late Spring and Autumn Period, an ancient Chinese thinker and politician Home, educator, founder of Confucianism.
Laozi: His surname is Li Ming'er, his courtesy name is Dan, his first name is Boyang, or his posthumous title is Boyang. He was born in the late Spring and Autumn Period. His birth and death dates are unknown. He is an ancient Chinese thinker, philosopher, writer and historian. The founder and main representative of Taoism.
Zhuangzi: named Zhou, a Mongolian native of the Song Dynasty during the Warring States Period, a thinker, philosopher, writer, and representative of the Taoist school in the middle Warring States Period. Together with Laozi, he is also known as "Laozi and Zhuangzi".
Mencius: His name was Ke, his courtesy name was Ziyu, and he was a native of the state of Zou (now southeast of Zoucheng, Shandong). He was a philosopher, thinker, politician, and educator during the Warring States Period. He was a representative figure of the Confucian school after Confucius and before Xunzi. Together with Confucius, he was called "Confucius and Mencius".
Sun Tzu: Ming Wu, courtesy name Changqing, was born in Le'an, Qi State (now northern Shandong Province) in the late Spring and Autumn Period. He was a famous military strategist and politician in the Spring and Autumn Period of China. He was also known as the Soldier of War or Sun Tzu (Sun Wuzi). He is called the "Sage of Military Strategies" and is known as the "Master of Military Strategies of All Ages" and "The Originator of Oriental Military Science".
Zengzi: Mingshen (shēn), courtesy name Ziyu, was born in Wucheng, South of Lu State (Jiaxiang County, Shandong Province) in the late Spring and Autumn Period. He is a famous Chinese thinker and one of the late disciples of Confucius. He studied under Confucius with his father Zeng Dian and is an important representative of the Confucian school.