platinum-iridium adj.
Standard, against which all others of the same category are
measured. Usage: silly. The notion is that one of whatever it is
has actually been cast in platinum-iridium alloy and placed in
the vault beside the Standard Kilogram at the International
Bureau of Weights and Measures near Paris. (From 1889 to 1960,
the meter was defined to be the distance between two scratches in
a platinum-iridium bar kept in that same vault -- this replaced
an earlier definition as 10^(-7) times the distance between the
North Pole and the Equator along a meridian through Paris;
unfortunately, this had been based on an inexact value of the
circumference of the Earth. From 1960 to 1984 it was defined to
be 1650763.73 wavelengths of the orange-red line of krypton-86
propagating in a vacuum. It is now defined as the length of the
path traveled by light in a vacuum in the time interval of
1/299,792,458 of a second. The kilogram is now the only unit of
measure officially defined in terms of a unique artifact.) "This
garbage-collection algorithm has been tested against the
platinum-iridium cons cell in Paris." Compare golden.