A secretary was an individual that assisted another in organising and managing an office.
Molly Wright was secretary to the dean of the school of history at the University of Frodsham in 1983. (AUDIO:The Lady Of Mercia)
Idris Hopper was Margaret Blaine's secretary. He failed to stop the Ninth Doctor entering her office as she fled through a window. (TV: Boom Town)
Donna Noble was a temporary secretary at H.C. Clements when she first met the Tenth Doctor. (TV: The Runaway Bride)