This comprehensive and authoritative dictionary provides clear definitions of units, prefixes, and styles of weights and measures within the Syst?me International (SI), as well as traditional, and industry-specific units. It also includes general historical and scientific background, covering the development of the sequential definitions and sizing of units. This new reference work will prove invaluable to professional scientists, engineers, technicians as well as to students and the general user. ? Over 1,600 clear and concise entries complete with historical background ? Covers a broad range of disciplines, including astronomy, electromagnetics, geology, photography, mathematics, meteorology, physics, and temperature ? Notes on associated terminology ? Numerous tables, including the geochronologic scale and the equation of time ? Comprehensive coverage of the whole Syst?me International