The word is from the Old French (c. 1300) disner, meaning "dine", from the stem of Gallo-Romance desjunare ("to break one's fast"), from Latin dis- (which indicates the opposite of an action) + Late Latin ieiunare ("to fast"), from Latin ieiunus ("fasting, hungry").[3][4] The Romanian word dejun and the French déjeuner retain this etymology and to some extent the meaning (whereas the Spanish word desayuno and Portuguese desjejum are related but are exclusively used for breakfast). Eventually, the term shifted to referring to the heavy main meal of the day, even if it had been preceded by a breakfast meal (or even both breakfast and lunch).
