Here's why it's called a "ghost":
* Ephemeral: It's brief and quickly disappears, like a ghost that vanishes in the blink of an eye.
* Subtle: It's barely there, almost imperceptible, similar to how a ghost is often unseen.
* Implied: It suggests the presence of something that is not fully manifested, much like a ghost is a spectral presence.
This expression is often used to describe a character who is trying to suppress their emotions, or who is feeling conflicted. It can also suggest that a person is trying to be polite or restrained, but is struggling to maintain their composure.
Here are some examples of how "a ghost of a smile" might be used in a sentence:
* "A ghost of a smile played on her lips as she listened to his story."
* "He forced a ghost of a smile, trying to appear happy."
* "The detective saw a ghost of a smile on the suspect's face, which made him suspicious."
The phrase captures the essence of a delicate, almost imperceptible expression that speaks volumes about a person's inner state.