The total time a customer must wait to receive a product after placing an order. When a scheduling and production system is running at or below capacity, lead time and Throughput Time are the same. When demand exceeds the capacity of a system, there is additional waiting time before the state of scheduling and production, and lead time exceeds throughput time.
(Lean Manufacturing Glossary)
Other Definitions
Lead Time – The time required by one task before another task can begin.(Wideman Comparative Glossary of Common Project Management Terms v2.1)
Lead Time – An overlap between tasks that have a dependency. For example, if a task can start when its predecessor is half finished, you can specify a finish-to-start dependency with a lead time of 50 percent for the successor task. You enter lead time as a negative lag value. (Wimincken.com PM Glossary)
Lead Time – The amount of time it takes for a shipment to arrive once an order has been placed. (http://erc.msh.org/fpmh_english/gloss/gloss_l.html)
Lead Time (a.k.a. overlap) – Task two starts before Task 1 ends in a controlled manner. A lead time is expressed by a negative (-) sign in MS Project. Units can have all duration labels from the duration table or can be a percentage (%).
Lead Time – An overlap between tasks that have a dependency. For example, if a task can start
when the previous task is half finished, you can set up a finish-to-start dependency
with a lead time of 50 percent. Lead time is entered as a negative lag value (http://www.techassoc.com/project2000/documents/project_glossary.pdf)