the third generation of a family, technology, or group

A massive 20-volume collection of inscriptions from Shang and Zhou dynasty ritual bronzes, compiled by Luo Zhenyu; though it lacks explanatory text, it remains a foundational 20th-century resource for ancient bronze inscriptions due to its vast scope.

three generations of a family living together in the same household

wealth does not last beyond three generations; a proverb suggesting that family fortunes are often lost by the third generation