What does the 'bo' in pho bo refer to?

The “bo” in pho bo refers to beef. In Vietnamese, bò means beef, so phở bò is beef noodle soup—the classic form of pho made with a clear, aromatic broth, rice noodles, and various cuts of beef.

Pho developed in northern Vietnam in the early 20th century, especially around Hanoi and Nam Dinh. Beef became more widely available during the French colonial period, and cooks built a deeply flavored broth from bones, onions, ginger, and spices such as star anise and cinnamon.

The name can be confused with bo vien, which means beef meatballs, or pho tai, which means pho topped with thinly sliced rare beef. Pho ga is the chicken version, while pho chay is vegetarian. Regional recipes also differ: northern pho is usually lighter and clearer, while southern versions often taste sweeter and arrive with more herbs and bean sprouts.