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on one's honor

Idioms  

  1. Entrusted to behave honorably and honestly without supervision. For example, The students were on their honor not to consult notes during the exam. Originally alluding to a solemn oath, this idiom dates from the mid-1400s.

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.