noun, noun or participle which takes 'suru'
calendar reform; adoption of a new calendar system
Refers to the official change from one calendar system to another, such as the Meiji-era switch from the lunar to the Gregorian calendar.
明治時代に改暦が行われ、太陽暦が採用された。
A calendar reform was carried out in the Meiji period, and the solar calendar was adopted.
noun
new calendar (for a new year); new year
Used for a fresh calendar at the start of a new year, often in the context of replacing an old one. This sense is less common than the reform sense.
年末に新しい改暦を買って壁に掛けた。
At the end of the year, I bought a new calendar and hung it on the wall.