Or rather the words breakfast, lunch, and dinner.
That’s easy—it’s an English word that developed to connote the first bit of food taken after a person wakes up. They’ve been sleeping, and so not eating, which means any food is “breaking the fast” they’ve been engaged in.
As late as the mid-20th century, dinner referred to the meal eaten in the middle of the day, not the one eaten at the end. Oddly enough, the word dinner comes from the 11th century Old French word disner, which meant “to eat breakfast.” As the word was absorbed into English as dinner, it came to refer to the “main” meal of the day, the timing of which changed over the centuries. Over time, the largest meal of the day moved later and later in the day, until it was the evening meal.
As dinner became established as a meal eaten in the evening or at night, there came a need for a meal in the middle of the day…or for some kind of sustenance. Lunch is short for luncheon, a word dating to the 1650s that once meant “thick hunk,” as in a thick hunk of meat. At the same time, there was an English word nuncheon, which meant a midday meal. That word is a combination of “noon” and an obsolete word schench, which meant “to have a drink.”
While it might seem like the notion of having a small meal in between the other, bigger meals seems like a modern invention or the result of advances in marketing and food storage technology, the word “snack” dates all the way back to the 1300s. It’s from a Middle Dutch word, snacken, which means to snatch or to snap—like a jaw quickly scaring down some food. The first written use of snack as a noun dates to the late 18th century. A few decades later, and people in Europe and the Americas were using “snack” as a verb to refer to eating a little bit of something to get them through a few hours.