Latitude measures degree from the equator and longitude measures the degree from the prime meridian, each corresponding to the x-axis and y-axis of the world. However, normally when we are talking about axes we say the x-axis and then y-axis, so it should be longitude and latitude, but we refer to it the other way. Why is this?
Latitude is an absolute (North-South) reference frame easily determined by reference to the positions of stars and was used long ago by navigators. Longitude is a reference frame relative to an arbitrary starting line (conventionally taken as the Greenwich Meridian). Longitude could most easily be determined by comparing the time of the sun’s zenith at Greenwich with its time at the position of the navigator. This was only possible once accurate clocks had been developed. The most significant advances were made as late as the 1700s.
It therefore seems reasonable to assume that humanity was first and long ago accustomed to speaking of latitude, with later awareness of longitude. There has been no subsequent disruptive technological influence that would have changed that order.
A good account of the clocks is given by Dava Sobel in her book
It is interesting to note that techniques for measuring longitude existed long before clock technology advanced enough to be effective. The enormous difficulties of these techniques are exemplified by the efforts of Chinese astronomers in the late Middle Ages. The method involves long observation of many stars over periods of years, is esoteric, and is too long even to summarise here. It is described in: