Select the most appropriate one-word substitution for the given group of words.

A person who is trained for travelling into space

astronaut

The most appropriate one-word substitution for a person who is trained for traveling into space is astronaut.

• Pilot is a person who operates the flying controls of an aircraft.
• Physicist is a scientist who studies physics, the natural science that deals with matter and energy and their interactions.
• Scientist is a person who is engaged in scientific study or research.