Also found in: Medical, Acronyms, Wikipedia.
X unit[′eks ‚yü·nət]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
a unit of length equal to 1.002 X 10-13 m (or 1.002 X 10−3 Å). The x unit was introduced for expressing the wavelengths of X rays and gamma rays as well as the spacings of crystal lattices.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.