1. A chemical principle stating that the rate of a reaction is proportional to the product of the concentrations of the reactants
   "The law of mass action helps predict equilibrium in reversible reactions"
    
2. Collective action taken by a large group of people, often for political or social purposes
   "The mass action of protesters led to significant policy changes"
    
3. (neurology) the principle that the cortex of the brain operates as a coordinated system with large masses of neural tissue involved in all complex functioning
   "The theory of mass action challenges the idea of strict localization of brain functions";
   - mass-action principle

Derived forms: mass actions

Type of: principle, rule

Encyclopedia: Mass action