unused item; never-used item
Refers to an item that has never been used, often in the context of second-hand sales or auctions.
This is an unused item, but the box is slightly damaged.
I won an unused camera at an auction.
新品 means brand-new, typically from a store, while 未使用品 may be second-hand but never used.
中古 means second-hand or used, while 未使用品 explicitly states the item has never been used.
Compound of 未 (mi, 'not yet') + 使用 (shiyō, 'use') + 品 (hin, 'item').