Old English bece "beech," from Proto-Germanic *bokjon (cognates: Old Norse bok, Dutch beuk, Flemish boek, Old High German buohha, German Buche, Middle Dutch boeke "beech"), from PIE root *bhagos "beech tree" (cognate with Greek phegos "oak," Latin fagus "beech;" see fagus).Formerly with adjectival form beechen. Also see book, n..