by definition

by definition idiom
According to prior determination, as a given. For example, This antibiotic is by definition the most effective now on the market. [1970s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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