1. An agent, especially a chemical agent such as caffeine, that temporarily arouses or accelerates physiological or organic activity.
2. A stimulus or an incentive: "An age of political excitement is usually a stimulant to literature" (Will Durant).
3. A food or drink, especially an alcoholic drink, believed to have a stimulating effect.
Serving as or being a stimulus; stimulating.
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.