One that acts in a specified manner: radiator.
[Latin -ātor : -ā-, stem vowel of verbs in -āre + -tor, agent n. suff. (later reanalyzed as -ātus, -ate + -or, -or).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
suffix forming nouns
a person or thing that performs a certain action: agitator; escalator; radiator.
[from Latin -ātor; see -ate1 -or1]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a suffix that forms nouns corresponding to verbs ending in -ate1, denoting a human agent (agitator; mediator) or nonhuman entity, esp. a machine (incubator; vibrator) performing the function named by the verb. Compare -tor, -or2.
[< Latin -ātor]
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