Theory of Constraints (TOC).

A management philosophy and set of tools for organizational change developed by Israeli physicist Dr. Eliyahu Goldratt and made famous through the book The Goal (1986) by Goldratt and Jeff Cox. TOC focuses on profit improvement by managing constraints (constraints): factors that hinder a company from achieving its goals. 

The primary focus is on removing or managing constraints to improve production, while Lean focuses on identifying and eliminating waste to improve the flow of value. Both Lean and TOC focus on improving the entire system rather than individual components. 

Lean Lexicon

Explanation of key Lean terms online
View the entire lexicon