1. The state or process of acting or doing: The medical team went into action.
2. Something that is done or accomplished; a deed. See Usage Note at act.
3. Organized activity to accomplish an objective: a problem requiring drastic action.
4. The causation of change by the exertion of power or a natural process: the action of waves on a beach; the action of a drug on blood pressure.
5. Habitual or vigorous activity; energy: a woman of action.
6. often actions Behavior or conduct.
7. Law A proceeding brought before a court to obtain relief; a lawsuit.
a. Armed encounter; combat: missing in action.
b. An engagement between troops or ships: fought a rear-guard action.
9. The most important or exciting work or activity in a specific field or area: always heads for where the action is.
a. A movement or a series of movements, as of an actor.
b. Manner of movement: a horse with fine action.
c. The appearance of animation of a figure in painting or sculpture.
a. The series of events and episodes that form the plot of a story or play: The action of the novel takes place over 40 years in the South.
b. A series or number of fast-moving, exciting, or dangerous events, especially in a movie: liked the film because there was so much action.
a. The operating parts of a mechanism.
b. The manner in which such parts operate.
c. The manner in which a musical instrument can be played; playability: a piano with quick action.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.