Is there a reason why [中]{ちゅう}[古]{こ} means used/second-hand items ?


I am learning Kanji using Kanji Damage deck on Anki and I came across this
vocabulary for 古:

> [中]{ちゅう}古{こ} の XXX : used XXX

If I try to literally translate 中古:

> [中]{ちゅう}(middle/central) + 古{こ}(old) = middle old ?

After a quick search on wictionary, I found that one of the etymology for the
word says it is Japanese invention
([link](https://en.wiktionary.org/wiki/%E4%B8%AD%E5%8F%A4)).

> Wasei kango (和製漢語), borrowing from Japanese [中]{ちゅう}古{こ}‎ (chūko,
> “secondhand”)

Is there a reason why 中 is used with 古 here while [古]{ふる}[着]{ぎ} means old/used
clothes without any need of 中 ?




While it does mean _middle ages_ in historical context when you pronounce it
ちゅうこ{HHLL}, the "secondhand" definition (read ちゅうこ{LLHH}) is unrelated to
that.

In this word
[中【ちゅう】](http://dictionary.goo.ne.jp/jn/142924/meaning/m0u/%E4%B8%AD/) stands
for "not completely (being one side); so-so":

> **２** 程度・価値・等級・序列などがなかほどであること。良くも悪くもないこと。

So 中古 literally means "half-old", that is not worn down to a nub, still
usable. Historically the reading
[ちゅうぶる](http://dictionary.goo.ne.jp/jn/143665/meaning/m0u/%E3%81%A1%E3%82%85%E3%81%86%E3%81%B6%E3%82%8B/)
is first attested, but it's almost dying out as far as I know.

> _Is there a reason why 中 is used with 古 here while 古着 means old/used clothes
> without any need of 中 ?_

That's complicated, but mostly because it's an established word. Not so many
words attached by 古- actually mean "secondhand". 古着, 古本 and 古道具 maybe?
Otherwise they'll mean really old.

> **古本** 、 **中古** コミック、 **中古** 漫画の買取や購入は日本最大級のコミック通販サイト ネットオフをご利用ください。
> ([Source](http://www.netoff.co.jp/index.jsp))

FYI there is a derived word 新古 to mean un-used goods that aren't able to be
sold as new stocks for some reason.




While it does mean _middle ages_ in historical context when you pronounce it
ちゅうこ{HHLL}, the "secondhand" definition (read ちゅうこ{LLHH}) is unrelated to
that.

In this word
[中【ちゅう】](http://dictionary.goo.ne.jp/jn/142924/meaning/m0u/%E4%B8%AD/) stands
for "not completely (being one side); so-so":

> **２** 程度・価値・等級・序列などがなかほどであること。良くも悪くもないこと。

So 中古 literally means "half-old", that is not worn down to a nub, still
usable. Historically the reading
[ちゅうぶる](http://dictionary.goo.ne.jp/jn/143665/meaning/m0u/%E3%81%A1%E3%82%85%E3%81%86%E3%81%B6%E3%82%8B/)
is first attested, but it's almost dying out as far as I know.

> _Is there a reason why 中 is used with 古 here while 古着 means old/used clothes
> without any need of 中 ?_

That's complicated, but mostly because it's an established word. Not so many
words attached by 古- actually mean "secondhand". 古着, 古本 and 古道具 maybe?
Otherwise they'll mean really old.

> **古本** 、 **中古** コミック、 **中古** 漫画の買取や購入は日本最大級のコミック通販サイト ネットオフをご利用ください。
> ([Source](http://www.netoff.co.jp/index.jsp))

FYI there is a derived word 新古 to mean un-used goods that aren't able to be
sold as new stocks for some reason.

