About
甲子 is formed by combining the first character from the ten Heavenly Stems (甲) with the first character from the twelve Earthly Branches (子), creating a compound that specifically denotes the initial pair in the sequential system used for marking years in the traditional Chinese sexagenary cycle.
Word Definition - 甲子
first of 10 heavenly trunks 天干 and first of 12 earthly branches 地支; the 60 combinations of heavenly stems and earthly branches (甲子, 乙丑, 丙寅 etc) making up the traditional Chinese calendar cycle; first year (A1) of the 60 year cycle, e.g. 1984 or 2044