part of speech
n. pl. parts of speech
1. One of a group of traditional classifications of words according to their functions in context, usually including the noun, pronoun, verb, adjective, adverb, preposition, conjunction, interjection, and article.
2. One of a group of theoretical classifications of words according to their syntactic, morphological, and semantic properties, such as the noun, determiner, verb, adjective, adverb, complementizer, preposition, and conjunction.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.