From Wikipedia:
Dinner is the main meal of the day, usually eaten around the evening, consisting normally of a combination of cooked animal or vegetarian proteins (meat, fish or soy), vegetables, and starch products like rice, noodles, or potatoes.
The word "dinner" comes from the French word dîner, the "chief repast of the day", ultimately from the Latin disiunare, which means to break fast (as in the English word "breakfast"). A dinner can also be a more sophisticated meal, such as a banquet.
According to the American Heritage Dictionary, the word "dinner" referred to breakfast in Middle English. It derives from late Latin disiunare (to break fast) which has also provided both the French déjeuner (breakfast or lunch, depending on region) and dîner (supper or lunch, depending on region). The Spanish word desayuno, or "breakfast," also comes from this Latin root.
In well-off families in England during the mid-17th century, dinner was served at any time between 11 a.m. and noon and was a rich, heavy, alcoholic repast that lasted for anything up to 3 or 4 hours. After the repast proper, the men would stay at the table to smoke, chat, and drink, while the women would retire to a boudoir to talk, sew, and brew tea.
Then, during the 18th century, dinner was served at a gradually later and later hour until by the early 1800s, the normal time of this meal in upper-class households was between 7 and 8.30 p.m., an extra repast called luncheon having been created to fill the midday gap.
So you see it can be a lengthy and a bit special full lunch or supper. So let's stop calling our ordinary, regular suppers, "dinner" simply because it is wrong and honestly a bit annoying to listen to specially from an average Filipino family (unless you belong to the illustrados) to use the word "dinner" everyday when they really mean supper.