The Spanish word "peruano" (meaning "Peruvian") combines two elements: "Perú" and the suffix "-ano". The country name "Perú" itself comes from "Biru", which was the name of a Panamanian chief encountered by Spanish explorers in the early 16th century. The suffix "-ano" is a common Spanish ending that denotes origin or belonging, similar to the English "-an" or "-ian".

When Spanish conquistadors were exploring Central America, they heard references to "Biru" and eventually this name evolved into "Perú", becoming the name for the wealthy empire they encountered in South America. Adding the suffix "-ano" to "Perú" created the adjective "peruano" to describe people and things from Peru.

Many Spanish words use the same suffix "-ano" to indicate origin, such as "mexicano" (Mexican), "colombiano" (Colombian), and "cubano" (Cuban). This pattern makes it easy to recognize and form adjectives of nationality in Spanish.

While "Peru" and "Peruvian" in English come from the same origin as "peruano", there aren't many direct English cognates since the word comes from an indigenous American source. However, English uses a similar pattern with the suffix "-ian" to form "Peruvian", just as it does with other nationality words like "Brazilian", "Colombian", and "Canadian".