A perennial plant or simply perennial (Latin per, "through", annus, "year") is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials. More correctly, woody plants like shrubs and trees are also perennials.

Perennials, especially small flowering plants, grow and bloom over the spring and summer and then die back every autumn and winter, then return in the spring from their root-stock rather than seeding themselves as an annual plant does. These are known as herbaceous perennials. However, depending on the rigors of local climate, a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings or from divisions.

The symbol for a perennial plant, based on Species Plantarum by Linnaeus, is , which is also the astronomical symbol for the planet Jupiter.