The virtual lack of gravity experienced by astronauts in space. The term is more accurate than ‘zero gravity’ or ‘weightlessness’, both of which imply a complete absence of gravity. The environment of microgravity is excellent for experiments concerning chemicals and materials, as conducted in the Microgravity Science Laboratory. The phenomenon also causes space sickness.

https://www.nasa.gov/centers/marshall/news/background/facts/microgravity.html News of NASA's microgravity research programme.

http://www.esa.int/esapub/onstation/os1.pdf The ESA’s On Station newsletter of the Directorate of Manned Spaceflight and Microgravity.