1911 Encyclopædia Britannica/Fresco

FRESCO (Ital. for cool, “fresh”), a term introduced into English, both generally (as in such phrases as al fresco, “in the fresh air”), and more especially as a technical term for a sort of mural painting on plaster. In the latter sense the Italians distinguished painting a secco (when the plaster had been allowed to dry) from a fresco (when it was newly laid and still wet). The nature and history of fresco-painting is dealt with in the article Painting.