Après-ski is the eating, drinking, sitting-around, and sometimes dancing that people do when they come off the mountain after skiing. Think warm rooms, wet boots by the door, hot drinks, beer, snacks, and talk about the day’s runs. It can also describe the clothes and mood that go with that — thick socks, a jumper, a holiday feel. You do not have to have skied well, or even at all, to join in; the word is about the social time after the snow, not about a special kind of skiing. It is a French borrowing, so it still feels a bit “resort” and a bit international. People who do not ski may never use it. In adverts and travel writing it is common, and it can stretch to mean that whole cosy-after-sport lifestyle, even for someone who only bought the jumper.