space station

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large satellite equipped to support a human crew and designed to remain in orbit around Earth for an extended period and serve as a base for launching exploratory expeditions, conducting research, repairing satellites, and performing other space-related activities.

from the GNU version of the Collaborative International Dictionary of English.

• noun a manned artificial satellite orbiting the earth designed for extended occupation and use by multiple crews in succession.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a manned artificial satellite designed for long-term habitation, research etc.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a manned artificial satellite in a fixed orbit designed for scientific research