It is a deciduous shrub or small tree growing to 4-5 m tall. The leaves are opposite, simple oval to lanceolate, 6-13 cm long and 4-9 cm broad, with a finely serrated margin; they are densely downy on the underside, less so on the upper surface. The hermaphrodite flowers are small (5 mm), creamy-white, produced in dense cymes 4-10 cm diameter at the top of the stems; they are produced in early summer, and pollinated by insects. The fruit is an oblong drupe 8 mm long, green at first, turning red, then finally black at full maturity, and contains a single seed. The seeds are dispersed when birds eat the fruit, then deposit the seeds in another location in their droppings.
An older name for the plant is hoarwithy. 'Hoar' means white and is in reference to the white hairs under the leaves, whilst 'withy' means a pliant stem.
The fruit is mildly toxic, and may cause vomiting or diarrhoea if eaten in large amounts.