noun
vintage item; period piece
Refers to an item that was produced or was popular during a particular past period, often used in the context of collectibles, antiques, or retro goods.
この店では昭和の当時品を扱っています。
This shop deals in vintage items from the Showa era.
祖母の家から大正時代の当時品が出てきた。
A period piece from the Taisho era turned up at my grandmother's house.
レトロ describes a style or atmosphere reminiscent of the past, whereas 当時品 refers to actual items from that period.
Compound of 当時 (とうじ, 'at that time') and 品 (ひん, 'item'). The exact historical derivation is uncertain, but the term is straightforwardly understood as 'item from that time'.