littering (n.)youdaoicibaDictYouDict[littering 词源字典]
1540s, of animals, "process of bringing forth young in a single birth," verbal noun from present participle of litter (v.). Meaning "act of furnishing with bedding" is from c. 1600. That of "act of dropping litter" is from 1900.[littering etymology, littering origin, 英语词源]