Oldness and antiquity with

The kanji has the straightforward meaning of something old or from long ago.

Etymology

In its later written form, this kanji is shown as 十 over 口. Traditional explanations connect it with something passed down through many mouths across many generations, making it ancient and longstanding.

Antiquity

(Ancient times)

古代(こだい) means ancient times or antiquity, especially in historical writing.

It combines 古 (old) with 代 (generation) to show an old age of history.

Manga panel from カードキャプターさくら showing example of Dueling like in Ancient Rome with 古代.
カードキャプターさくら » Volume 3 » Page 21

Li seems fired up over something with Sakura. Yamazaki suggests whatever the issue is be settled when they play badminton during that day’s physical education class. Li asks why things have to be settled via badminton.

山崎(やまざき):
()らないの?バドミントンっていうのはね 古代(こだい)ローマから(つた)わる由緒(ゆいしょ)(ただ)しい決闘(けっとう)方法(ほうほう)でね」
“You don't know? Badminton is a time-honored method of dueling that has been passed down since ancient Rome.”
()けたほうはもう それはひどいめに……」
“The loser suffers a truly terrible fate.”
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Classical Texts

(Classical Japanese)

古文(こぶん) means classical Japanese writing or literature, especially works from the Edo period or earlier. In school, it also names the study of such texts.

It combines 古 (old) with 文 (writing) to show old writing or a classical text.

Manga panel from あずまんが大王 showing example of Studying classical Japanese with 古文.
あずまんが大王 » Volume 1年生 » Page 34

Following the a midterm exam, Yomi asks Tomo how it went.

とも:
古文(こぶん)はなんのために勉強(べんきょう)するの?」
“What's the point of studying classical Japanese?”
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Practice and Learning

(Practice)

稽古(けいこ) means practice or training, especially in martial arts, performing arts, and other traditional disciplines. It can also mean a lesson or training session in one of those arts.

It combines 稽 (examine) with 古 (old) to show practice rooted in studying established ways.

Manga panel from 名探偵コナン showing example of Koto lessons with 稽古.
名探偵コナン » Volume 6 » Page 27

Hired to confirm whether a client’s wife is having an affair, Kogoro reveals a candid photo he took of the wife with another man. The client mentions he let his staff take a break so they wouldn’t know about Kogoro’s visit. Kogoro asks if that includes the client’s wife.

伝次郎(でんじろう):
「いや… 稲子(いねこ)(こと)稽古(けいこ)があるといって昼前(ひるまえ)勝手(かって)()かけたよ」
“No... Ineko said she had a koto lesson and went out on her own before noon.”
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