The word "litter" can refer to various concepts depending on the context. Generally, it means the waste materials or trash that are scattered about, especially in public places, creating mess and pollution. Litter can also refer to a group of young animals born to a mother at the same time, like puppies or kittens.
The word "litter" comes from the Middle English "litere," which means "to bed or to cover with bedding," derived from the Old French "litiere," and has roots in Latin "lectus," meaning "a bed." The modern usage referring to waste material began to gain popularity in the 19th century.