(physics) geometrical optics

a high school (upper secondary school) with a large portion of graduates entering elite universities; a prep school

(physics) spectroscopy

calendar / era

the Gregorian calendar

history (record or narrative description of past events) / a person's background, career, or personal history

(geology) conglomerate

revision of the calendar (e.g. from lunar to solar) / change of calendar at the start of the year

revise the calendar / change the calendar at the start of the year

Alternative spelling of 歴青