The Latin word tempora, a possible source of “tempura,” refers to the Christian observance known as the Ember Days. In Latin, tempora means “times” or “periods,” and the phrase was associated with recurring seasons of fasting and abstinence.
Ember Days are quarterly observances traditionally held on Wednesday, Friday, and Saturday during four periods of the Western Christian liturgical year. They were days of prayer, fasting, and abstinence; fish and vegetables were acceptable foods when meat was avoided. Portuguese missionaries may have used this religious vocabulary when introducing battered fried vegetables and seafood to Japan in the sixteenth century.
That culinary connection is often linked to peixinhos da horta, a Portuguese dish of battered and fried green beans. The cooking technique reached Japan through Portuguese contact, especially around Nagasaki, and eventually developed into modern tempura.
The etymology is not certain. Another proposed explanation connects “tempura” with the Portuguese words tempero or temperar, meaning seasoning or to season. Still, among the choices given, Ember Days is the established answer for the tempora theory.