loco

the english word 'loco' has a dual etymology leading to its two distinct meanings. the noun, short for 'locomotive', is a 19th-century american english clipping. it derives from the latin 'locus' (place) via 'locomotive', literally meaning "moving from place to place." the adjective meaning "crazy" entered english in the mid-19th century from american spanish, where 'loco' means "insane." this spanish term is believed to come from the mapuche (indigenous south american) word 'loco' or 'luqu', referring to a certain plant that causes livestock to behave erratically after ingestion. thus, the two homographs converged in english spelling from entirely different linguistic and cultural journeys.

this word is a loanword and a clipping, treated as a simplex form in modern english. it originates from the spanish word 'loco' meaning 'insane'.