What does "frog" mean?

Additional senses

1. 2.(Railroads) A supporting plate having raised ribs that form continuations of the rails, to guide the wheels where one track branches from another or crosses it.
2. 3.Etym: [Cf. fraco of wool or silk, L. floccus, E. frock.] An oblong cloak button, covered with netted thread, and fastening into a loop instead of a button hole.
3. 4.The loop of the scabbard of a bayonet or sword. Cross frog (Railroads), a frog adapted for tracks that cross at right angles. -- Frog cheese, a popular name for a large puffball. -- Frog eater, one who eats frogs; -- a term of contempt applied to a Frenchman by the vulgar class of English. -- Frog fly. (Zoöl.) See Frog hopper. -- Frog hopper (Zoöl.), a small, leaping, hemipterous insect living on plants. The larvæ are inclosed are frothy liquid called cuckoo spit or frog spit. -- Frog lily (Bot.), the yellow water lily (Nuphar). -- Frog spit (Zoöl.), the frothy exudation of the frog hopper; -- called also frog spittle. See Cuckoo spit, under Cuckoo.
4. 5.To ornament or fasten (a coat, etc.) with trogs. See Frog, n., 4.