Secondhand
Used
noun, の adjective
The combination of kanji doesn't make perfect sense, but it's alright. Take something that's middle old and you have something that's used or secondhand. It's not 100% old yet... it's still in the middle, meaning you can give it to someone else to use, like your younger siblings.
ちゅうこ
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
中古ですが、ベンツをかいました。
It’s used, but I bought a Benz.
このあたりは、中古ショップがじゅうじつしています。
There are a lot of secondhand stores in this area.
中古のかぐのような人とはけっこんしたくない。
I don’t want to get married to someone who is like a piece of used furniture.