diameter

Definitions

General Science

  • noun the distance across the widest part of a circle or a tube

Astronomy

  • The full width of a celestial object, measured either in units of distance or of angular measure as seen from the Earth or some other point

Aviation

  • noun the distance from one side of a circle to the other, passing through the centre

Cars & Driving

  • noun the length of a straight line through the centre of a circular object connecting two directly opposite points on its circumference

Construction

  • The line in a circle passing through its center. Also refers to the nominal diameter designated by an approved material standard.
http://www.dictionarycentral.com/definition/diameter.html