Whisker/ˈwɪskər/ Definition 1 of 4Pro Tip 1/2Animal Sensory Hairs Whiskers on animals provide sensory information; they're not just for looks. When navigating tight spaces, a mouse uses its whiskers to feel the way. Pro Tip 2/2Not Regular Fur Animal whiskers are different from their fur; they're thicker and more sensitive. The dog's whiskers quivered, detecting even the slightest breeze.