The longest diameter of an ellipse or ellipsoid.
Related Terms 
DEFLECTION

PNEUMATIC ATOMIZER
An atomizer that uses compressed air to produce drops in the diameter range of 5100 micrometers.

PILOT BIT
A noncoring bit with a cylindrical diamondset plug of somewhat smaller diameter than the bit proper, set in the center and projecting beyond the main face of the bit.

OVERSQUARE ENGINE
An engine with bore diameter greater than the stroke length.

OUTSIDE DIAMETER
The outer diameter of a pipe, including the wall thickness; usually measured with calipers. Abbreviated OD.

OPEN WELL
1. A well whose diameter is great enough (1 meter or more) for a person to descend to the water level. 2. An artificial pond filling a large excavation in the zone of saturation up to the water table.

N ROD BIT
A Canadian standard noncoring bit having a set diameter of 2.940 inches (74.676 millimeters).

MOUNT ROSE SNOW SAMPLER
A particular pattern of snow sampler having an internal diameter of 1.485 inches (3.7719 centimeters), so that each inch of water in the sample weighs 1 ounce (28.3495 grams).

MINOR DIAMETER
The diameter of a minor diameter minor loop cylinder bounding the root of an external thread or the crest of an internal thread.

MINIMUM TURNING CIRCLE
The diameter of the circle described by the outermost projection of a vehicle when the vehicle is making its shortest possible turn.
