: a straight line that runs from one side of a figure and passes through the center <Measure the diameter of the circle.>
: the distance through the center of an object from one side to the other :thickness<the diameter of a tree trunk>
Word Root of DIAMETER
The Greek word metron, meaning “measure,” gives us the root metr. Words from the Greek metron have something to do with measuring. A thermometer is an instrument that measures temperature. A diameter is the measurement across the center of a circle. The metric system is a system used for measuring size, weight, and volume. A perimeter is the measurement of the outside of a figure or shape.
Medical Definition of DIAMETER
: a unit of magnification for an optical instrument equal to the number of times the linear dimensions of an object are apparently increased <a microscope magnifying 60 diameters>
: one of the maximal breadths of a part of the body <the transverse diameter of the inlet of the pelvis>