From Old Galician-Portuguese cousir (“to examine”) (13th century, Cantigas de Santa Maria), ultimately from Gothic 𐌺𐌰𐌿𐍃𐌾𐌰𐌽 (kausjan), from Proto-Germanic *kauzijaną (“to choose, taste, test”), from Proto-Indo-European *ǵews- (“to choose, taste”). Compare French choisir, English choose.