E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A fore-and-aft sail set upon the mizen-mast of a three-masted vessel, and the jigger-mast of a four-masted vessel. There is no spanker in a one- or two-masted vessel of any rig. A spanker used to be called a driver. (Supplied by an old sailor of long service.)