A part of the trunk or a large branch of a tree that has fallen or been cut off. An official record of events during the voyage of a ship or aircraft. An apparatus for determining the speed of a ship, originally consisting of a float attached to a knotted line wound on a reel, the distance run out in a certain time being used as an estimate of the vessel's speed. Enter (an incident or fact) in the log of a ship or aircraft or in another systematic record. Cut down (an area of forest) in order to exploit the timber commercially. Natural logarithm (a logarithm to the base e ). Logic.