swear by

phrasal verb·1 sense·particle by

Meanings

1

Strongly believe in the value or effectiveness of something

Why “by”? BY shows the thing that guides you: a rule, promise, name, or belief.

He swears by that brand.
He strongly believes that brand is the best.
My aunt swears by ginger tea.
My aunt strongly believes ginger tea is effective.

Don't confuse with

swear byswear off

Swear by means strongly believe in the value or effectiveness of something. Swear off means promise yourself you will stop doing or using something.

Test yourself

He swears by that brand. What does it mean?

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