noun

1. the doing of something; state of being in motion or of working
2. an act or thing done
3. behavior; habitual conduct
4. habitual activity characterized by energy and boldness a man of action
5. the effect produced by something the action of a drug
6. the way of moving, working, etc., as of a machine, an organ of the body, etc.
7. the moving parts or mechanism, as of a gun, piano, etc.
8. 1. the sequence of happenings in a story or play; plot
   2. any of such happenings
   3. such happenings when exciting
9. a legal proceeding by which one seeks to have a wrong put right; lawsuit
10. 1. a military encounter
    2. military combat in general
11. the appearance of animation in a painting, sculpture, etc.
12. Slang activity or excitement; specif., gambling activity

Etymology: ME accion < OFr action < L actio < pp. of agere: see act

noun