An oblong is a rectangle that does not have all equal sides. A square is not an oblong, but any other type of rectangle is.
An oblong can also describe any shape that is longer than it is wide. For instance, an oval is also considered oblong. Some common examples are a piece of paper or a spaghetti squash. The word originated from the French word "oblonge," which came from the Latin word "oblongus." It first came into English in Middle English. Essentially, the Latin word means "long," from "longus" and "towards," from "ob"; in other words, leaning toward being long rather than short.