a. One who operates a machine or device: the operator of a forklift.
b. The owner or manager of a business.
c. A military person who executes a special operation.
d. Informal A person who is adept at accomplishing goals through shrewd or unscrupulous maneuvers.
2. Mathematics A function, especially one from a set to itself, such as differentiation of a differentiable function or rotation of a vector.
3. A logical operator.
4. Genetics A chromosomal segment of DNA that regulates the activity of the structural genes of an operon by interacting with a specific repressor.
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.