n. pl. dic·tion·ar·ies
1. A reference work containing an alphabetical list of words, with information given for each word, usually including meaning, pronunciation, and etymology.
2. A reference work containing an alphabetical list of words in one language with their translations in another language.
3. A reference work containing an alphabetical list of words in a particular category or subject with specialized information about them: a medical dictionary.
4. A list of words stored in machine-readable form for reference, as by spelling-checking software.
[Medieval Latin dictiōnārium, from Latin dictiō, dictiōn-, diction; see DICTION.]
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.