The meal supper is another of the many English borrowings from French where our first written evidence is from around 1300. Old French soper, meaning “supper”, is derived from Old French sope, meaning “soup”, the traditional evening meal at the time. English soup was also borrowed from sope in the same time period. It makes sense that food terms from the more prestigious language tended to stick.
Sope is descended from Late Latin suppa, meaning “sopped bread”. I could imagine a food getting named after the thing you use to eat it. The part I found hard to believe is that Latin suppa is an ouroboros-like borrowing from Proto-Germanic supô, originally a form of “to drink”. Supô also has a direct English descendant that doesn’t improbably go through French: soap.
Maybe the synonym dinner has a less silly origin story? It’s another of those 1300s borrowings from Old French, in this case from disner, meaning… “lunch”. Disner is descended from Vulgar Latin disiūnāre, also meaning “lunch”, which is in turn from Late Latin dis- + iēiūnāre, which means “fast” as in time without eating. It’s from Latin “break fast”. Incredible.