# swear by

CEFR B2 · Phrasal verb

Source: https://englishreference.com/word/swear-by
Updated: 2026-10-23

## Definition

to believe strongly that something is effective or useful because you have used it yourself.

For teachers: to express total confidence in the efficacy or value of a particular thing, often based on personal experience. Transitive and inseparable; the object is typically a product, method, or remedy.

## Examples

- My grandmother swears by honey for a sore throat.
- Many professional athletes swear by this specific brand of shoes to prevent knee injuries during long runs.
- While some critics dismissed the new software, the design team continued to swear by its intuitive interface and robust features.

## Pitfalls

- Not "I swear by to drink green tea." but "I swear by drinking green tea." — the preposition 'by' must be followed by a noun or a gerund (-ing form), not an infinitive.

## Usage notes

- always followed by a noun or gerund representing the thing trusted.
- Teaching tip: contrast with 'swear at' (to use bad language) to show how the preposition completely changes the meaning of the base verb.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.