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swear by (someone or something)
1. To have and proclaim one's complete faith or confidence in someone or something. Not everyone believes that magnets have healing properties, but I've sworn by them for years—they're the only thing that's given me relief from back pain! You should ask our accountant to have a look at your tax returns. He's always been able to save us money, so we swear by him!
2. To make a very serious, solemn pledge or oath, especially that something will happen or that one is telling the truth. The person or thing following "by" is typically someone or something that one loves or respects. I swear by my mother's grave that I will get revenge on the people who wronged you. He swore by God that he was telling the truth.
3. To be certain of or sure about something. That should fix the connectivity issues with the servers, but I can't swear by it until I've had a chance to run some tests.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.
swear by someone or something
1. Lit. to utter an oath on someone or something. I swear by Jupiter that I will be there on time. She swore by her sainted mother that she would never do it again. The sheriff swore by his badge that he would lock her up if she ever did it again.
2. Fig. to announce one's full faith and trust in someone or something. I would swear by Roger any time. He is a great guy, and he tells the truth. I swear by this computer. It has always served me well.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
1. Have great reliance on or confidence in, as in She swears by her personal physician. [Early 1800s]
2. 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]
3. Take an oath by, as in I swear by all the saints in heaven. [Early 1200s]
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.
1. To have great reliance on or confidence in someone or something: He swears by his personal physician. She swears by the new computer program.
2. To have reliable knowledge of something; be sure of something: I think that's the person who stole my purse, but I couldn't swear by it.
3. To take an oath by something: I swore by all the angels and saints of heaven that I wouldn't reveal the secret to anyone.
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.