Lean

Lean is a waste-free approach to process management.

Definition

According to Managing Quality by Foster (6th edition),

Lean. A waste-free approach to process management.

According to Juran's Quality Handbook by Defeo (7th edition),

Lean. The process of optimizing systems to reduce costs and improve efficiency by eliminating product and process waste; also the state of a system after such optimization.

According to the ITIL Foundation 4e by Axelos,

Lean. An approach that focuses on improving workflows by maximizing value through the elimination of waste.