op·er·a·tive (ŏpər-ə-tĭv, -ə-rā′tĭv, ŏprə-)
1. Being in effect; having force; operating: "Two major tendencies are operative in the American political system" (Heinz Eulau).
2. Functioning effectively; efficient.
3. Engaged in or concerned with physical or mechanical activity.
4. Of, relating to, or resulting from a surgical operation.
5. Significant; most important; key: The operative word is "low-fat."
1. A skilled worker, especially in industry.
a. A secret agent; a spy.
b. A private investigator.
3. One who works for a political organization, often wielding influence out of public view.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. 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.