I will use a smile as an example (though the word should work in general for something which is "at the edge").
So what I want is an adjective for a half-smile which would fit in, say, the following sentence
... a smile; subtle and ______ .
Here are some possibilities which I already looked at but fail to satisfy my description:
- extreme: Literally means something at the extremity or end, but it is not usually used in the physical sense so it would convey a different meaning.
- subtle: Doesn't contain the meaning I want which is physically at the edge or corner.
- quasi: Again doesn't describe the location of the smile, also cannot stand alone as an adjective.
- crooked: Fits the sentence I provided but doesn't mean "at the edge".
- lopsided: Like crooked.
- uneven: Same problem.
I already checked out this question A word that refers to a "half-smile"? but the answers either provide a noun or an adjective which doesn't have the meaning of "at the edge".