Vestigial/veˈstɪdʒiəl/ Definition 1 of 3Pro Tip 1/3Size Implication Vestigial often implies something was bigger or more important in the past. The deserted shopping mall stands as a vestigial monument of consumerism. Pro Tip 2/3Evolutionary Trace Used in biology to describe parts that have declined in size and function. Whales have vestigial leg bones, remnants of their walking ancestors. Pro Tip 3/3Not Always Useless Although usually non-functional, vestigial items can sometimes have new uses. The pigeon's vestigial toes are used for balance rather than grasping.