Pronunciation: [swˈe͡ə bˈa͡ɪ] (IPA) 
The spelling of "swear by" may seem straightforward, but it can be tricky for non-native speakers due to the silent "e" at the end of "swear." The phonetic transcription for this word is /swɛr baɪ/. The "a" sound in "swear" is pronounced like the "a" in "cat," while the "y" sound in "by" is pronounced like the "i" in "bit." Overall, the phrase means to have great confidence in the truth or effectiveness of something.
The phrase "swear by" is an idiomatic expression that can be interpreted in various ways, depending on the context. Broadly speaking, it means to have absolute trust or confidence in something or someone, often to the point of relying on it as a guarantee or ultimate authority.
In a literal sense, "swear by" refers to taking an oath or making a solemn declaration, typically invoking a divine being as a witness. This action underscores the seriousness and conviction behind one's affirmation or promise.
Metaphorically, when someone says they "swear by" something, they are expressing unwavering faith or belief in its effectiveness, reliability, or value. It implies that the person considers that thing to be their go-to or trusted resource for a particular purpose. For example, someone might claim to "swear by" a particular brand of painkiller because they have consistently found it to be highly effective in relieving their discomfort.
"Swear by" can also imply a personal endorsement or recommendation, suggesting that the speaker highly values and relies on the person or thing being mentioned. It conveys a strong sense of confidence and reliability in the subject, indicating that the speaker believes others should have the same trust in it.
Overall, "swear by" represents a profound level of confidence and trust in the object or individual being referred to, often based on personal experience or reputation.
The phrase "swear by" has its origins in Old English. The word "swear" comes from the Old English word "swerian", which meant to promise or take an oath. "By" is a preposition that also comes from Old English and denotes the agency or means through which an action is done. Thus, "swear by" originally meant to make a promise or take an oath using something or someone as a witness or guarantee. Over time, the phrase has evolved to also imply having deep trust or belief in something or someone, even without making an actual oath.
