 The term is commonly reported to be a contraction of the Portuguese expression "abre os olhos" ("open the eyes") or "abri vossos olhos" ("keep your eyes open"), but this has been shown to be a false etymology.In the Portuguese language of the time, "abrolhos" meant "spiked obstructions", and served not only as a word for offshore reefs, but also as their word for caltrops and chevaux de frise.To Spanish ears, however, the word sounded like "abre ojos" ("open your eyes"), so they imputed this meaning, and this false etymology was later borrowed by English, Dutch and French writers.