- The definition of an astronaut is a person who either travels into space or who is trained to travel into space.
An example of an astronaut is Neil Armstrong, the man who walked on the moon.
An astronaut floating in space.Licensed from iStockPhoto
Origin: ; from French astronaute: see astro- and amp; aeronaut
Used by arrangement with John Wiley & Sons, Inc.
Origin: astro- + Greek nautēs, sailor (from naus, ship; see nāu- in Indo-European roots).
astronaut - Cultural Definition
A crew member of a space mission launched by the United States. (See Apollo program and Mercury program.)