A bulbil (also referred to as bulbel, bulblet, and/or pup) is a small, young plant that is reproduced vegetatively from axillary buds on the parent plant's stem or in place of a flower on an inflorescence. These young plants are clones of the parent plant that produced them—they have identical genetic material. The formation of bulbils is a form of asexual reproduction, as they can eventually go on to form new stand-alone plants.

Although some bulbils meet the botanical criterion to be considered a true bulb, there are a variety of different morphological forms of bulbils, some of which are not considered to be bulbs. Hence the reason for distinction between bulbs and bulbils. For example, some bulbous plant groups, like onions and lilies, produce bulbils in the form of a secondary, small bulb. Onion and lily bulbils meet the botanical criterion to be labeled a true bulb. All bulbils produced by bulbous plants are to be considered bulbs, but not all bulbils are to be considered bulbs. For example, other non-bulbous plant groups, like various genera within the subfamily Agavoideae, are well known to produce bulbils that do not actually meet the botanical criterion to be considered a bulb.