Multiplier onion is a term used to describe a variety of onions that produce clusters of bulbs rather than a single bulb. Usually grown by small-scale farmers, multiplier onions have become increasingly popular among chefs and home gardeners looking for unique flavors and textures. Synonyms for multiplier onion include potato onion, shallot onion, walking onion, tree onion, top-set onion, and perennial onion. These names reflect the different properties of the onion - for example, walking onion is so named because it produces small bulbils on the top of its stem that can be replanted to create new onion clusters. Similarly, tree onion grows tall like a tree and produces a cluster of bulbs on top.