Definition: stock keeping unit (SKU)

Stock keeping unit (SKU):

"Warehousing item that is unique because of some characteristic (such as brand, size, color, model) and must be stored and accounted for separate from other items. Every SKU is assigned a unique identification number (inventory or stock number) which is often the same as (or is tied to) the item's EAN or UPC."

Source: BusinessDictionary.com

In the picture below you can notice in the inventory window SKU.Image source