In what year did pho first appear in a Chinese-Vietnamese dictionary? The answer is 1931.
Historical reviews distinguish between early written appearances and dictionary definitions. The word phở appeared in Vietnamese literature in 1907, while references describe street-vendor sales by 1913. Those dates do not indicate the first dictionary entry.
A 1931 Vietnamese dictionary is identified as the first to define phở as a soup. Its definition describes a dish made from thin slices of rice cake boiled with beef. Therefore, 1907 confuses the earliest literary evidence with the first dictionary record.