Merriam-Webster's Collegiate® Dictionary, 11th Edition
DIRECTORY
I. adjective
Date: 15th century
serving to direct,
II. noun (plural -ries)
Etymology: Middle English directorie guide, from Medieval Latin directorium, from neuter of Late Latin directorius directorial, from Latin dirigere
Date: 1543
1. a book or collection of directions, rules, or ordinances, an alphabetical or classified list (as of names and addresses), a body of directors, folder 3b