log [ME] The word log is first recorded in the Middle Ages in the sense ‘a bulky mass of wood’. The ship’s log [M19th] or official record of events during the voyage got its name from a device used from the late 16th century to find out the rate of a ship’s motion, a thin quarter-circle of wood loaded so as to float upright in the water and fastened to a line wound on a reel (see knot). The captain would record the information obtained from this in a journal, or log. See also jam, sleep.