What is the meaning of 片頬で笑う?


Does it describe that reserved sort of smile, when you slightly raise just one
corner of your mouth?  
Or a smirk?

Or is it an idiom that shouldn't be taken literally?




片頬 means "one cheek" (one of a pair (片) + cheek (頬) = one cheek (片頬)). So,
片頬で笑う would mean to smile with only one side of your face (which I assume is
what you meant in the first sentence of your question).

I don't think this on its own is an idiom, but after research I did find one
idiom that contains the phrase:
[男は三年に片頬笑う](https://dictionary.goo.ne.jp/jn/260503/meaning/m0u/). It describes
a man who only smiles like this very rarely (i.e. "once every three years")
because smiling too much will damage his dignity.




片頬 means "one cheek" (one of a pair (片) + cheek (頬) = one cheek (片頬)). So,
片頬で笑う would mean to smile with only one side of your face (which I assume is
what you meant in the first sentence of your question).

I don't think this on its own is an idiom, but after research I did find one
idiom that contains the phrase:
[男は三年に片頬笑う](https://dictionary.goo.ne.jp/jn/260503/meaning/m0u/). It describes
a man who only smiles like this very rarely (i.e. "once every three years")
because smiling too much will damage his dignity.

