a. Perception of visual, auditory, tactile, olfactory, or gustatory stimuli in the absence of any external objects or events and with a compelling sense of their reality, resulting from certain mental and physical disorders or as a response to a drug.
b. The objects or events so perceived.
2. A false or mistaken idea.
hal·lu′ci·nation·al, hal·luci·na′tive adj.
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.