idyllic

“a hundred days of sermonizing, one fart” → a metaphor for how something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

Kyūjitai form of 大日本帝国: Empire of Japan

(military, historical) the Imperial Japanese Army

(military, historical) the Imperial Japanese Navy

(mathematics) geometrical

"Historical kana usage", a prescriptive method of using kana to write Japanese. Devised in the Edo period by Keichū (契沖) and taught in schools until 1946, it aims to be etymologically faithful and reflects earlier stages of the language (Heian period and earlier).

humanitarian

hostile takeover

experimental study