mammal - any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk

fur - dense coat of fine silky hairs on mammals (e.g., cat or seal or weasel)

wool, fleece - outer coat of especially sheep and yaks

hair - dense growth of hairs covering the body or parts of it (as on the human head); helps prevent heat loss; "he combed his hair"