中古（品）って英語でなんて言うの？

You can also use the term pre-owned which is short for an item previously owned by someone else.

If you are specifically looking for second-hand items, shopping at a thrift store would
be ideal as everything there will be a second-hand item.

"Hand me down", is usually used in reference to clothing that was previously worn by a family member and passed on down to you.
"Unnew" the opposite of new.
"Antique" a very old item, by their very nature all antiques are used goods.

These terms all refer to items that have been owned by someone else before.

Second hand - can include - books, clothes, phones, etc. "Second hand clothes shop".
(number of) Owners - normally you would use this with cars, boats, motorbikes. "This car has had 2 owners".
Used condition - Can be used for laptops, tablets, computers, cars, boats. You would normally use this if you were the first owner. "Laptop for sale, used condition".

"second hand" means that the product was used before.
The product is not brand new.

All of these expressions refer to items that were used before.
A hand-me-down item is one that has been passed from one person to the other.
Here are some example sentences:-
1. I went to the thrift store to buy some previously used clothes, that were still in good condition.
2. Since I had two older brothers, I always had to wear their hand-me-down clothes.
3. I bought some nearly new books on Amazon for half the price.

We can use the words 'used' or 'secondhand' for goods that have already been used before they've been received or purchased. If you purchased them from a リサイクルショプ you can call it 'recycled goods'.

If they are goods passed down from an older child to a younger child, we would call that a 'hand-me-down'. Example, "I got these hand-me-down (clothes) from my older sister".

Second-hand things are not new and have been owned by someone else.
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Examples :
Buying a second-hand car can be a risky business.
Our father could afford only second-hand cars.
This applies to new and second-hand items.
It was like buying a second-hand car.
We bought so many second-hand clothes.

A) Pre-loved goods - previously owned or used; second-hand. Contemporary definitions for preloved. adjective. secondhand; previously owned or used; also written pre-loved.

B) Second - hand goods - A secondhand or used good is one that is being purchased by or otherwise transferred to a second or later end user. A used good can also simply mean it is no longer in the same condition as it was when transferred to the current owner.

I hope this helps :-)

Second-hand (adjective)
This term describes something that had a previous owner. In other words it's not new.
Concept stems from the current owner not being the FIRST owner, but rather the SECOND owner.

Example
A: I plan on purchasing a new car?
B: That's going be costly. You should consider buying a second-hand car.
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Pre-owned (adjective)
'pre-' (prefix) - means before in time, order or place.
In other words the item was owned before the current owner purchased it.

Example
A: Do you like my car?
B: Yes, I do. It's in good condition for a pre-owned vehicle.

Any of these phrases is appropriate.

Goods that are not new can be called:
used
secondhand
pre-owned
previously owned

In English, a product that is not used (i.e someone has used it before), is most commonly referred to as "Second hand" or "Used goods".

Example sentence: I found a hair dryer that is second hand and as a result of it not being new, it was sold to me at a discount price.

I always used the second option and I believe it's a more common way to say in England, although, the first option is good too.For example - I always buy second-hand clothes because it's much cheaper