Work-In-Process (WIP)

Also known as "work in progress", it refers to unfinished items that are still in production. As unfinished items, they reflect the least valuable capital because they don't yet meet the customer's requirements (value) and are no longer raw materials (i.e., they are not re-sellable as raw materials). It generally requires additional storage and is often a victim of the 7 deadly wastes (e.g., over-production, waiting, inventory, etc.).
Related StatStuff Video: 
   -Section 2-Lean, Lesson #7 - Work in Process (WIP)