What does it mean if someone is described as "green around the gills"?

Describing someone as "green around the gills" typically refers to their appearance suggesting that they are unwell or sick. This expression originates from the idea that a person might look pale or slightly yellowish, akin to a fish that may appear greenish near its gills when it is not feeling well or is dying. This idiomatic phrase evokes the imagery of illness, particularly nausea or pallor, which aligns with the notion of someone looking unwell.

The other options do not fit this idiomatic expression. The phrases about exceeding expectations, being very costly, or making a great effort all convey positive or neutral meanings, while the focus of "green around the gills" is specifically linked to feeling poorly or looking ill.