chinquapin [Algonquian], name for certain American species of the chestnut genus of the family Fagaceae (beech family) and for a related species, the golden chinquapin (Castanopsis chrysophylla), an evergreen of the Pacific states. The common chinquapin is Castanea pumila, native to the E United States. Its wood and fruit are used like those of the chestnut. The bush chinquapin (C. alnifolia) has a more southern range. Chinquapin is classified in the division Magnoliophyta, class Magnoliopsida, order Fagales, family Fagaceae.