Tempera is derived from the Italian "dipingere a tempera" ("paint in distemper"), from the Late Latin "distemperare" ("mix thoroughly"). 

Tempera also known as egg tempera is a permanent, fast-drying painting medium consisting of pigments mixed with a water-soluble binder medium, usually glutinous material such as egg yolk. Tempera also refers to the paintings done in this medium. Tempera paintings are very long-lasting, and examples from the first century AD still exist. Egg tempera was a primary method of painting until after 1500 when it was superseded by oil painting. 

Tempera painting has been found on early Egyptian sarcophagus decorations. Many of the Fayum mummy portraits use tempera, sometimes in combination with encaustic painting with melted wax, the alternative painting technique in the ancient world. It was also used for the murals of the 3rd century Dura-Europos synagogue. 

(References: Wehlte, Wikipedia)

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