In science, action is the product of work and time: 
where A here stands for "action", W for work, and t for time.
In philosophy, generally tracing to the human movement theories of Greek philosopher Aristotle, what is called “action theory” or theories of “action” attempt to debate or theorize about “will” in the context of materialism, physicalism, and or other types of non-reductive chemical physical materialism, often alluding to the notion that “free will” and or consciousness or conscious “choice” to make an action are aspects of an emergent property.  Cuban-born American philosopher Alicia Juarrero puts it like this: 
“The philosophical literature of action has remained trapped in [a] peculiar combination of Aristotelian and Newtonian views of causality.”(add discussion)
● Action chains
● Action thermodynamics
● Mechanical action
1. Perrot, Pierre. (1998). A to Z of Thermodynamics (pg. 4). Oxford University Press.
2. Deacon, Terrence W. (2011). Incomplete Nature: How Mind Emerged from Matter (action, 35+ pgs). W.W. Norton & Co.
3. Juarrero, Alicia. (1999). Dynamics in Action: Intentional Behavior as a Complex System (action, 95+ pgs). MIT Press.
● Osborn, Henry F. (1916). The Origin of Life: on the Theory of Action, Reaction and Interaction of Energy (pg. xi). The Science Press.
● Kennedy, Ivan R. (2001). Action in Ecosystems: Biothermodynamics for Sustainability (ch. 4: Action Thermodynamics, pgs. 65-98). Research Studies Press.
● Action (physics) – Wikipedia.
● Action theory (philosophy) – Wikipedia.
● Social actions – Wikipedia.