Middle English: from Old French disner, probably from desjëuner 'to break fast', from des- (expressing reversal) + jëun 'fasting' (from Latin jejunus).

• dinner from Middle English:

  Our words dine (Middle English) and dinner are both from the same root, Old French desjeuner ‘to have breakfast’, which survives in modern French as déjeuner, ‘lunch’, and petit déjeuner, ‘breakfast’. The root was jëun ‘fasting’, which goes back to Latin jejunus ‘fasting, barren’ found also in jejune (early 17th century) which originally meant ‘without food’ and then ‘not intellectually nourishing’. In Australia, New Zealand, and Canada to be done like a dinner is to be utterly defeated or outwitted—the British equivalent is done like a kipper. The messy and unappetizing appearance of food set out for a dog is behind the expressions a dog's dinner (or breakfast), meaning ‘a poor piece of work’ a mess', and dressed up like a dog's dinner, ‘wearing ridiculously smart or ostentatious clothes’, which date from the 1930s.