Why do russians called astronouts as cosmonouts ??

Answer 1

1. The word "astronaut" is a generic term for a person who travels in space. It may be freely translated as "cosmonaut", "spationaut", "taikonaut", and so forth. Different conventions apply for different home countries. Russians retain the name "cosmonaut", while Europeans traveling through ESA are translated to "astronauts". The term "astronaut" is used in the Outer Space Treaty to refer to all space travelers (although it presumed that all would be official representatives of their nations).
2. The word "Astronaut" and "Cosmonaut" etc. are also titles referring to members of their nation's "Astronaut/* Corps".
3. From NASA usage, an astronaut or cosmonaut does not change their title by flying on another nation's craft. An astronaut launching to ISS on a Soyuz is still an astronaut. References to "cosmonaut training" (and vice versa) indicate that it's considered a skill rather than a title.
4. The Fédération Aéronautique Internationale defines astronautical flight as anything exceeding the Karman line or 100km altitude. The FAI has also (post-Tito) offered a definition of Astronaut in its Sporting Code as both "crew members and to scientific personnel aboard the spacecraft playing an active part in the mission during the flight." The 100km line is respected by Russia, who terms members of its corps "test-cosmonaut" until they fly. Other agencies do not appear to follow this and simply certify people based on training.
5. NASA and Russia both have launched individuals who were not members of the astronaut/* corps: payload specialists and research cosmonauts. Other "guests" have been given training and official designation as astronauts/* but are still considered to have earned the title. Jean-Loup Chrétien, for example, was a cosmonaut for Russia and an astronaut for the US, while remaining a French spationaute.
6. NASA and Russia agreed in 2002 not to call space tourists astronauts or cosmonauts, but space flight participants. (In a prior ruling, NASA had termed Dennis Tito a "nonprofessional cosmonaut".)

Answer 2

because they have their own culture, including habits, food, roles, social structure, government, fashion, money, terms, AND language----- both languages have a deep root from Latin.

cosmos is derived from Greek (latin), meaning 'everything' as in "the universe"
astro is derived from Greek too, meaning 'star'
naut is also derived from Greek, meaning sailor

so, we're both using almost the same word.
might as well be the same difference as saying

chair, or seat

Answer 3

Because they're exploring the cosmos.