From Longman Dictionary of Contemporary Englishcat litterˈcat ˌlitter (also kitty litter American English) noun [uncountable] DHPa substance like small grey stones that people put in boxes for cats that live indoors, and which the cats use as a toilet
Examples from the Corpus
cat litter• Fill this with a small amount of cat litter, having lined it first with newspaper.• You can use a large plastic cat litter tray as a dirt-box. 