Critical mass

What is Critical mass ?

Critical mass is (noun) 1. the smallest amount of material required for a nuclear chain reaction 2. a point or situation which must be reached before a change occurs 3. the number of customers or size of market share that allows a business to begin to make money 4. the point in software development at which a piece of software acquires so many features that it stops being useful

 

source: Easier English, Student Dictionary Upper Intermediate Level