Why is the ninth month called September?
1940, a word invented from initial letters in long-range navigation.
A long-range navigational system, in which a receiver's position is determined by an analysis involving the time intervals between pulsed radio signals from two or more pairs of ground stations of known position. The difference in the timing of the received signals corresponds to differences in distance from the transmitters, and the position of the receiver can be calculated by triangulation. Compare Global Positioning System.