English

Noun

space group ‎(plural space groups)

1. (crystallography, mineralogy) The set of all symmetry operations that can be applied to a given crystal without changing it.
   • 1998, Georgina Ferry, Dorothy Hodgkin: A Life:

     Dorothy also learned to identify the space group of a molecule, an essential prerequisite for finding the structure, by looking for spots that were missing from the regular array in an X-ray photograph.