In Argentina and Uruguay, croissants are called medialunas because their shape resembles half moons.
The Spanish word medialuna literally means “half moon,” matching the pastry’s curved form. Medialunas are commonly eaten with coffee at breakfast, during an aperitivo, or at merienda, the afternoon snack period. They are a familiar part of bakery and café culture in both countries.
Two common varieties are medialunas de manteca, made with butter and typically sweetened or glazed, and medialunas de grasa, made with lard. The butter version is usually sweeter, while the lard version may be less sweet and somewhat more bread-like.
Medialunas resemble French croissants but are not always identical in texture or preparation. The term is therefore more than a translation used casually by tourists: it is the local name for a distinct regional pastry tradition. Kifli, gipfeli, and cornetti are related crescent pastries from other culinary traditions, not the answer here.