horn of plentyDefinition of horn of plenty noun 1a cornucopia. 2an edible woodland mushroom with a funnel-shaped cap that bears spores on its greyish outer surface, found in both Eurasia and North America. Craterellus cornucopioides, family Cantharellaceae, class Hymenomycetes horn of plenty in other Oxford dictionaries Definition of horn of plenty in the US English dictionary