A secco – The art or an example of painting on dry plaster. In The Secret Supper, it's indicated that Leonardo da Vinci used this technique because he never intended for The Last Supper "to be long-lasting."

Art of perspective – The representation of solid objects and three-dimensional space according to optical perception, based upon converging lines meeting at a single fixed vanishing point. An artistic technique introduced during the Renaissance era.

Bonhommes – Good men; the name by which the ancient Cathars referred to themselves.

Bottega – An artist's studio.

Cathars - A Christian sect that flourished in western Europe in the 12th and 13th centuries; considered heretical for beliefs contrary to those of the Catholic Church.

Cenacolo – The colloquial term by which The Last Supper was known in Milan.

Coptic – Afro-Asiatic language spoken in Egypt from about the 2nd century A.D.

Disciple – One who embraces and assists in spreading the teachings of another. In The Secret Supper, it refers to an apprentice of Leonardo da Vinci.

Fresco - The art of painting on fresh, moist plaster with pigments dissolved in water, or a painting executed in this way.

Heterodox - Contrary to or differing from some acknowledged standard, especially in church doctrine or dogma; holding unorthodox opinions or doctrines.

Inquisitor - One who inquires or makes an inquisition, especially a questioner who is excessively rigorous or harsh.

Maestà – The colloquial term by which Leonardo's da Vinci’s Virgin of the Rocks was known.

Palazzo – A mansion or palace.

Piazza – A public square or plaza.

Refectory - A room where meals are served, especially in a college or other institution, such as the monastery at Santa Maria delle Grazie.

Twelfth Night - January 5th, the eve of Epiphany, celebrated as a holiday in parts of Europe and the United States and marked by feasting, merrymaking, and the lighting of bonfires.