I have read about the term -- the best I found (don't know where) is that the term "frog" goes back to the early days of railroading.
The one report is that in that era a piece of woman's fancy jewelry that had a complex form to it was called a frog.
Another report (found on Wikipedia) it that "frog is taken from the part of a horse's hoof it most closely resembles." This same Wikipedia page also reports "On dual-gauge switches, a special frog is used where the third rail crosses the common rail. Denver and Rio Grande crews called this a 'toad'." While references are given at the bottom of the Wikipedia page, there are no footnotes within the write-up to provide a specific source.
Looking up the word frog at the Merrian-Webster dictionary website we find:
Quote
Definition of frog
1 : any of various largely aquatic leaping anuran amphibians (such as ranids) that have slender bodies with smooth moist skin and strong long hind legs with webbed feet — compare toad
2 : the triangular elastic horny pad in the middle of the sole of the foot of a horse — see hoof illustration
3 a : a loop attached to a belt to hold a weapon or tool
b : an ornamental braiding for fastening the front of a garment that consists of a button and a loop through which it passes
4 often capitalized, disparaging + offensive : frenchman
5 : a device permitting the wheels on one rail of a track to cross an intersecting rail
6 : a condition in the throat that produces hoarseness "had a frog in his throat"
7 : the nut of a violin bow
8 : a small holder (as of metal, glass, or plastic) with perforations or spikes for holding flowers in place in a bowl or vase
Many possibilities as where the name comes from. But the exact one may be lost to history.
It is interesting that a number of railroad terms have an origin with horses and that form of transportation. While we know the term "hostler" as being the man who would move locomotives at an engine terminal, the term goes back to the man who took care of carriage horses and riding horses at inns and roadhouses and other similar places.
Brian Norden
