sombrero Syllabification: (som·bre·ro)Pronunciation: /sämˈbre(ə)rō/Definition of sombrero noun (plural sombreros) a broad-brimmed felt or straw hat, typically worn in Mexico and the southwestern US. Origin:Spanish, from sombra 'shade' (see somber)sombrero in other Oxford dictionaries Definition of sombrero in the British & World English dictionary