Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
Linguis. a class made up of words that occur in a distinctive position in constructions and have certain formal features in common, as the form class noun in English, made up of all words to which both the plural and possessive suffixes may be added
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nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A set of words that have one or more grammatical or syntactic characteristics in common, such as the class of transitive verbs in English.