item number; product ID; reference number
Used in retail, inventory, and catalog contexts to refer to a unique identifier assigned to a product or item.
Please check the item number in the catalog.
Please provide the product ID when ordering.
商品番号 is a slightly more formal, retail-oriented synonym for 品番, both referring to a product's identifying number.
Compound of 商品 (product, merchandise) and 番号 (number). The exact historical derivation is straightforward; the word is a modern technical term.