An anticyclone is a large area of high air pressure. Air in the middle of it slowly sinks, and the weather underneath is often calm: clearer skies, lighter wind, and usually dry. Weather presenters more often just say high pressure; anticyclone is the science word for the same kind of system. A cyclone is the other way round — low pressure, and often rain or storms — and this word was built as the opposite of that. Sir Francis Galton coined it in the 1860s. Though actually the weather is not always pleasant. A summer anticyclone can sit still and give a heatwave; a winter one can bring fog or a hard frost. In the northern half of the world the wind around it moves in a clockwise ring; south of the equator it goes the other way. You will meet the word on weather maps and in geography, not much in everyday chat.

反氣旋