Определение mount st helens в Английский Язык Английский Язык словарь
a volcano in Washington State in the northwestern US, which erupted 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