geological period
Used in geology for named periods such as ジュラ紀 (Jurassic period). Often appears as a suffix in compound terms.
ジュラ紀は恐竜の時代として知られている。
The Jurassic period is known as the age of dinosaurs.
Nihon Shoki; Chronicles of Japan
Abbreviation of 日本書紀, the second oldest extant historical chronicle of Japan, completed in 720 CE. Used mainly in historical or academic contexts.
See also: 日本書紀
Kii Province
Historical abbreviation for 紀伊国, an old province covering present-day Wakayama and southern Mie. Rare outside historical references.
紀はかつて紀伊国と呼ばれた地域を指す。
Ki refers to the region once called Kii Province.
The Nihon Shoki records history from the age of the gods to Empress Jitō.
代 names larger geological eras (like 中生代), while 紀 names the smaller periods within an era (like ジュラ紀), so learners often mix up which scale each covers.
日本書紀 is the full title of Japan's ancient chronicle, while 紀 is its rare abbreviated form seen mainly in scholarly writing.
紀伊 is the full historical name of the old province, while 紀 is a rarer, shortened form of the same name.
century · era; age · of the century; epoch-making
travelogue; travel journal
public morals; discipline; social order
this century
era; epoch · Common Era; AD
bulletin; memoirs; journal
the Kojiki and Nihon Shoki
law and order; official discipline
biography; historical record
The kanji 紀 originally means 'record' or 'chronicle', and by extension came to be used for geological periods in modern scientific terminology. The abbreviation for Nihon Shoki and Kii Province derives from the first character of those names.
millennium
party discipline
official discipline; rules for officials
years; period of years · age
school discipline
years since the start of an era
marriageable age of a young woman; sweet sixteen
century; one century
Triassic period
Permian period
last century; previous century · ancient times; old times