1. One who keeps track of time; a timekeeper.
2. A timepiece, especially one used for measuring and signaling the end of time intervals, as on a stove.
3. A switch or regulator that controls or activates and deactivates another mechanism at set times.
4. A device that controls the timing of the sparks that ignite the fuel in an internal-combustion engine.
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.