butter wouldn't melt in someone's mouth

9.9

Seems very innocent and quiet but is not really kind

idiom

: parecer inocente

She looks so sweet, but I know butter wouldn't melt in her mouth.

Examples

He gave me a look so innocent—butter wouldn't melt in his mouth.
She acts so sweet, but butter wouldn't melt in her mouth when she wants something.
Don't believe her story; butter wouldn't melt in her mouth, but she's not as nice as she seems.
Why does everyone think butter wouldn't melt in his mouth?
Don't believe her story; butter wouldn't melt in her mouth, but she's not as nice as she seems.
She acts so sweet, but butter wouldn't melt in her mouth when she wants something.
He gave me a look so innocent—butter wouldn't melt in his mouth.

Antonyms

guilty

∞ 2.3

Responsible for doing something wrong and open to blame or punishment

deceitful

31 5.0

Acting in a dishonest way to make people believe something untrue

How Innocent

angelic

32 4.0

innocent

54 3.4

naive

312 4.1

butter wouldn't melt in someone's mouth

9.9

sly

31 4.9

malicious

89 5.8

Surface Forms

butter wouldn't melt in someone's mouth main

Morphology

butter + wouldn't + melt + in + someone's + mouth

The literal meanings of 'butter', 'melt', 'in someone's mouth' yield a physical image (butter not melting in a mouth) that does not transparently map onto the idiomatic meaning of appearing innocent or demure. This is a conventionalized, culture-specific idiom whose intended meaning cannot be reliably inferred by a B1 learner who only knows the constituent words, so it is non-compositional and unpredictable.

Etymology

The idiom butter wouldn't melt in someone's mouth comes from a simple image: someone looks so calm and proper that even butter would not melt in their mouth. That's why it is used to say someone seems 'innocent' or 'modest' even when they may not be.