St Hel ‧ ens, Mount /s ə nt ˈhelənz $ seɪnt-/ BrE AmE
a ↑ volcano in Washington State in the northwestern US, which erupted (↑ erupt ) in 1980 after a quiet period of over a hundred years, sending out ↑ ash (=powder produced when something has been burnt) and ↑ lava (=hot liquid rock) over a wide area. The large amount of ash in the air affected the weather in many northern parts of the world for some time.