dinneryoudaoicibaDictYouDict[dinner 词源字典]
dinner: [13] The etymological meaning of dinner is ‘breakfast’. The word comes ultimately from an unrecorded Vulgar Latin verb *disjūnāre, a compound formed from the prefix dis- ‘un-’ and jējūnus ‘fasting, hungry’ (source of English jejune [17]): hence, ‘break one’s fast’. Old French adopted it in two phases: as desiuner, which became modern French déjeuner (originally ‘breakfast’ but later ‘lunch’), borrowed by English in the 18th century; and as disner.

In later Old French this developed into diner (source of English dine [13]), which came to be used as a noun – from which English acquired dinner. In English it has always denoted the main meal of the day, although the timing of this has varied over the centuries, and continues to do so, according to region, social class, etc.
=> jejune[dinner etymology, dinner origin, 英语词源]
dinner (n.)youdaoicibaDictYouDict
c. 1300, from Old French disner (11c.), originally "breakfast," later "lunch," noun use of infinitive disner (see dine). Always used in English for the main meal of the day; shift from midday to evening began with the fashionable classes. Childish reduplication din-din is attested from 1905.