# butter wouldn't melt in someone's mouth

idiom

Source: https://englishreference.com/idiom/butter-wouldnt-melt-in-someones-mouth
Updated: 2026-08-10

## Meaning

The identified person appears to be benign, mild-mannered, or calm (but with an integral suggestion that, to the contrary, they really are untrustworthy, disagreeable, or mean-spirited).

## Examples

- He acts so sweet, but butter wouldn't melt in his mouth.
- She looks innocent enough, but butter wouldn't melt in her mouth when she is trying to get her way.
- Although he presented himself as a humble servant of the public, those who knew him best suspected that butter wouldn't melt in his mouth.

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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.