长大后我想当一名宇航员用英文怎么说

"Astronaut" 是英语中的宇航员的说法。这个词来源于希腊语 "astron"（星）和 "nautes"（水手）。

例句:

"I want to be an astronaut when I grow up." (长大后我想当一名宇航员)
"Being an astronaut is a childhood dream of mine." (当一名宇航员是我童年的梦想)
"Astronauts are the explorers of outer space." (宇航员是外层空间的探险家)