Sexagenary

Sexagenary is an English adjective meaning relating to sixty. It derives from Latin sexagenarius, from sexageni- sixty. The term is used in historical, astronomical, and calendrical contexts, and in some cases can describe a sixty-year period or a classification based on the number sixty. The related noun sexagenarian denotes a person aged sixty to sixty-nine.

In East Asian calendrical systems, the sexagenary cycle (often called the stem-branch cycle) is a sixty-year cycle formed by the repetition of ten heavenly stems and twelve earthly branches. Each year, month, day, or hour is paired with a stem and a branch, yielding a distinct designation. The stems, in traditional order, are Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui; the branches are Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai. The cycle begins anew when a pair recurs after sixty combinations. The cycle has been used for dating, astrology, and fortune-telling in China, Korea, Japan, and Vietnam, and it also appears in historical and literary contexts as a method of temporal labeling.

Usage in English typically refers to the sixty-year cycle or to more general senses of “relating to sixty.” The noun sexagenarian denotes a person aged sixty to sixty-nine, while sexagenary as an adjective can describe elements associated with sixty, such as time-keeping, age groups, or historical periods.