SMAIG, 289, a long chin, officiousness.
Those I spoke to in Eriskay who recognised the word pronounced it smuig. Under smuig, Dwelly says “Snout; face, in ridicule; snot, phlegm; Dirt, filth.” It seems to be used locally for the meaning “face, in ridicule”, with a definite hint of chin thrown in too: “Look at the smuig on her there. Gobby, a bit snobby maybe.” And the chin was thrust out to show us what that would look like [Eriskay]. “You’d get a smuig on somebody that’s a bit full of themselves.” [Eriskay]
It’s also been noted down as “a mischievous grin” in Garrynamonie.