point

(pt)

   1. a unit of angle measure equal to 1/32 of a circle. Compasses are read by suspending the compass needle over a compass card traditionally inscribed with a 32-point star. Each point of the star represents a named direction; for example, the first five points from north towards east are labeled North, North-by-East, North-Northeast, Northeast-by-North, and Northeast. The difference between two directions can be expressed as a certain number of these compass points. One point equals 11°15' of arc or pi/16 radians.

   2. a unit of length used by typographers and printers. When printing was done from hand-set metal type, one point represented the smallest element of type that could be handled, roughly 1/64 inch. Eventually, the point was standardized in Britain and America as exactly 1/72.27 = 0.013 837 inch, which is about 0.35 mm (351.46 micrometers). In continental Europe, typographers traditionally used a slightly larger point of 0.014 83 inch (about 1/72 pouce, 0.377 mm, or roughly 1/67 English inch), called a Didot point after the French typographer Firmin Didot (1764-1836). In the U.S., Adobe software defines the point to be exactly 1/72 inch (0.013 888 9 inch or 0.352 777 8 millimeters), a unit sometimes called the big point (bp). The German standards agency DIN has proposed that all these units be replaced by multiples of 0.25 millimeters (1/101.6 inch). See also kyu.

   3. a percentage point.

   4. a unit of mass used for precious stones such as diamonds. One point equals 0.01 carat, or exactly 2 milligrams.

   5. a unit of quantity equal to 1. This unit is used to express changes in an arbitrary score or index, such as the score in an athletic contest. In finance, a change of one point in the Dow Jones average or similar indices represents a change of 1.00 in the index.

   6. a unit used to represent the smallest significant change in an arbitrary ratio. This usage is common in sports. Most sports "averages" are actually ratios of successful performances divided by attempted performances; baseball's batting average is a good example. These ratios are computed to a fixed number of decimal places, usually three, and a point represents a change of 1 in the last decimal place. Thus the batting averages .314 and .302 are said to differ by 12 points.

   7. another name for a mil¹, a unit of distance equal to 0.001 inch. Points are used with this meaning to measure the thickness, or caliper, of paper or card stock in the paper industry. One point equals 25.4 micrometers or microns.

   8. a measure of the specific gravity of a liquid, typically used in brewing and winemaking. Specific gravity is the mass of a sample of the liquid divided by the mass of an equal volume of pure water. It is a dimensionless (unit-less) number, typically a little larger than 1. Each "point" represents an increase of 0.001 above 1. For example, a liquid of specific gravity 1.048 is described as 48 point.

   9. a medieval unit of time equal to 1/5 hour, or 12 minutes. The point was divided into 8 moments.