"A large nail or pin, generally of iron. The larger forms of spikes, particularly railroad spikes, are chisel-pointed, and have a head or fang projecting to one side to bite the rail. Spikes are also made split, barbed, grooved, and of other shapes." —Whitney, 1889
Illustration of two forked spikes. When driven into wood, the points spread and hook into the wood.
William Dwight Whitney, PhD, LLD The Century Dictionary: An Encyclopedic Lexicon of the English Language (New York, NY: The Century Co., 1895) 5831