Definition of perennials:
(adj) :
Lasting or remaining active throughout the year, for multiple years, or all the time.
(adj) :
(botany) Of a plant: active throughout the year, or having a life cycle of more than two growing seasons.
(n) :
(botany) A plant that is active throughout the year, or has a life cycle of more than two growing seasons.
(adj) :
(figurative) Continuing without cessation or intermission for several years, or for an undetermined or infinite period; never-ending or never failing; perpetual, unceasing.
(adj) :
(figurative) Appearing or recurring again and again; recurrent.
(n) :
(by extension) A person or thing (such as a problem) that appears or returns regularly.