# holy mackerel

idiom

Source: https://englishreference.com/idiom/holy-mackerel
Updated: 2026-08-10

## Meaning

An expression of surprise.

## Examples

- Holy mackerel, I forgot my keys.
- He opened the envelope and said, "Holy mackerel, I actually won the prize."
- Holy mackerel, she whispered, staring at the test results she had not dared to hope for.

## Origin

Recorded from 1803 with uncertain origin, but possibly a euphemism for Holy Mary, with Mackerel being a nickname for Catholics because they ate the fish on Fridays. Another suggested explanation is the practice of selling mackerel on Sundays in the seventeenth century (because its quality deteriorates rapidly), so it was known as holy fish. (disputed)

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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.