Spike comes from Middle English spik ('nail, sharp point'), probably from Old Norse spík ('splinter') or Middle Dutch spiker, ultimately of Proto-Germanic origin. The historical chain includes Old Norse spík and Proto-Germanic *spīkō. Older glosses in the chain include "nail, sharp point" and "splinter", which help explain the semantic range of the modern word. Morphologically, spike is best read as borrowing, yielding an English noun and verb shaped by both form history and later usage. In current English it functions as a noun and verb, with the sense "a thin pointed piece of metal, or a sharp sudden increase". English derivatives include spiky and spiked. The result is an English noun and verb whose etymology preserves the older forms while supporting the word's specialized modern meaning.