woyliePronunciation: /ˈwɔɪli/Definition of woylie noun (plural woylies) a nocturnal rat-kangaroo that has a tail with a black crest of hair and a bushy tip, which it uses to carry nest material. Bettongia penicillata, family Potoroidae. Alternative name: brush-tailed bettong Origin: 1920s: probably from an Aboriginal word of Western Australia