nebula
/ˈnebjʊlə/noun
(pl. nebulae /-liː/ 或nebulas)
1
- Astronomy a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter【天文】星云。
1.1
- (in general use) any indistinct bright area in the night sky, e.g. a distant galaxy（一般用语）雾影; 星云状物。
2
- Medicine a clouded spot on the cornea causing defective vision【医】薄翳, 角膜云翳。
词源
mid 17th cent. (as a medical term)： from Latin, literally 'mist'.