In horticulture, the term "perennial" is generally used for the category of plants that live for more than one year but are not substantially woody (even though trees and shrubs are technically perennial too).
In particular, the term is associated with flowering plants associated with cottage gardens and tradtional English-style gardens, such as salvias, chrysanthemums and many of the daisies.
(Argyranthemum, Gazania, Aster, Chrysanthemum, Osteospermum and others
Washington State University Clark County Extension
Advice for professional growers from Western Australia Department of Agriculture
Dianthus and Carnation
) Washington State University
Kentucky Garden Flowers, University of Kentucky
More to come in future updates