nebula
noun /ˈnebjələ/
/ˈnebjələ/
(plural nebulae
(astronomy /ˈnebjəliː/
/ˈnebjəliː/
)- a mass of dust or gas that can be seen in the night sky, often appearing very bright; a bright area in the night sky caused by a large cloud of stars that are far away
星云；外观似星云的星系 词源mid 17th cent. (as a medical term): from Latin, literally ‘mist’.