Etymology

Although its geographic origin is unknown, the disease was called Spanish flu from the first wave of the pandemic. Spain was not involved in the war, having remained neutral, and had not imposed wartime censorship. Newspapers were therefore free to report the epidemic's effects, such as the grave illness of King Alfonso XIII, and these widely-spread stories created a false impression of Spain as especially hard hit.

Alternative names were also used at the time of the pandemic. Similar to the name of Spanish flu, many of these also alluded to the purported origins of the disease. In Senegal it was named 'the Brazilian flu', and in Brazil 'the German flu', while in Poland it was known as 'the Bolshevik disease'. In Spain itself, the nickname for the flu, the "Naples Soldier", was adopted from a 1916 operetta, The Song of Forgetting (La canción del olvido) after one of the librettists quipped that the play's most popular musical number, Naples Soldier, was as catchy as the flu. Today, however, 'Spanish flu' (Gripe Española) is the most widely used name for the pandemic in Spain.

Other terms for this virus include the "1918 influenza pandemic," the "1918 flu pandemic," or variations of these.