mid-15c., "a guide;" 1540s, "a book of rules," especially ecclesiastical, "book of directions for saying various Church offices," from Medieval Latin directorium, noun use of neuter of Latin directorius, from directus, past participle of dirigere "to set straight,"(see direct (v.)).
Meaning "alphabetical listing of inhabitants of a region" is from 1732; sense of "listing of telephone numbers" is from 1908.
As "a board of directors" by 1803, especially in reference to the French Directoire, the five-man executive government of France from 1796 to 1799.
As an adjective, "guiding, directive," from mid-15c. As "of or resembling the style in fashion and decorative arts prevailing at the time of the Directoire," by 1878.