Mass action may refer to:
- Law of mass action, in chemistry, a postulate of reactions
- Mass action law (electronics), in semiconductor electronics, a relationship between intrinsic and doped carrier concentrations
- Mass action (sociology), in sociology, a term for situations in which a large number of people behave simultaneously in similar ways individually and without coordination
- Mass Action Principle (neuroscience), in neuroscience, the belief that memory and learning are distributed and can't be isolated within any one area of the brain
- Mass tort, or mass action, in law, which is when plaintiffs form a group to sue a defendant (for similar alleged harms)
Famous quotes containing the words mass and/or action:
“There is a small steam engine in his brain which not only sets the cerebral mass in motion, but keeps the owner in hot water.”
—Unknown. New York Weekly Mirror (July 5, 1845)
“Thought is the seed of action; but action is as much its second form as thought is its first.”
—Ralph Waldo Emerson (1803–1882)