The Oxford dictionary definition of longitudinal is (1) running lengthwise rather than across (not "length"), (2) relating to longitude; measured from east to west (sorry Schuyler, you're off by 90 degrees).
The comparable definition of latitudinal is "relating to the position of a place north or south of the earth's equator".
IOW, latitudinal does not seem to have a non-geographical definition in modern usage. But, it implicitly means perpendicular to longitudinal, which is why I have no real problem with the MCB/ARA/AAR usage for those short running boards at each end of many house cars. It is what it is.
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Dave Parker
Swall Meadows, CA
