A lily is any flowering plant of the genus Lilium. It grows from a bulb and produces a stem with leaves along its length, surmounted by its flowers. The stem dies away completely during the plant's winter dormancy. In art, lilies are commonly associated with Mary.
The word "lily" is used in the common names of many other plants, some of which are only distantly related or unrelated, such as the calla lily, which is actually an aroid.