WIP means Work in Process, or products that are partially complete.
Work in Process is one of the 3 inventory accounts used by a manufacturing concern. Let’s say we are working in a shoe factory. If we have leather in a warehouse that we hope to someday use to make shoes, the leather is raw materials inventory. The shoes that are partially complete are Work in Process Inventory, and the shoes that are finished and ready to be sold are Finished Goods Inventory.