swear by
Idioms-
Have great reliance on or confidence in, as in She swears by her personal physician . [Early 1800s]
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Also, swear to . Have reliable knowledge of, be sure of, as in I think she was going to the library but I can't swear to it . [Mid-1700s]
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Take an oath by, as in I swear by all the saints in heaven . [Early 1200s]
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
“At the end of the day, the government is going to go with systems that have been deployed, where combatant commanders swear by the fact that they want one of what we have,” Mengucci said.
From Barron's • Jan. 15, 2026
It’s true, some of the world’s top CEOs and elite athletes swear by early rising.
From The Wall Street Journal • Jan. 11, 2026
Some people swear by writing a song every day and finishing it, even if it’s bad.
From Los Angeles Times • Dec. 1, 2025
Tech moguls swear by it, Hollywood stars insist it keeps them trim.
From BBC • Aug. 30, 2025
“It’s the truth, Mata! I swear by Jupiter!”
From "Tiger, Tiger" by Lynne Reid Banks
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.
