1 a [noncount] : things that have been thrown away and that are lying on the ground in a public place
▪ We decided to pick up the litter in the park. ▪ roadside litter
b [singular] : a messy pile or group of things
▪ Her desk was covered with a litter of legal documents. 2 [noncount] a : dry material that is spread in a container and used as a toilet by animals (especially cats) while they are indoors
▪ cat/kitty litter ▪ (chiefly US) a litter box = (Brit) a litter tray [=a container holding litter for a cat]
b : soft and dry material (such as straw) that is spread on the ground for some animals (such as horses) to sleep on 3 [count] : a group of young animals that are born at a single time
▪ a litter of puppies/piglets ▪ He was the runt of the litter. [=the smallest animal in the litter] — often used figuratively in the phrase the pick of the litter ▪ Of all the cars on the market, this one is clearly the pick of the litter. [=the best one] 4 [count] : a covered bed that has long poles on the bottom and that was used in the past for carrying a very important person
▪ The emperor was carried to the palace on a litter.