a segment of the trunk of a tree when stripped of branches
"The lumberjack dragged the heavy log up the hill to stack it for winter heating."
a written record of messages sent or received
"they kept a log of all transmission by the radio station"
"an email log"
a written record of events on a voyage (of a ship or plane)
"The captain signed off on the log before docking in port."
measuring instrument that consists of a float that trails from a ship by a knotted line in order to measure the ship's speed through the water
"The captain checked the log before setting sail to ensure their knots were accurate for the long voyage."
The trunk of a dead tree, cleared of branches.
"The physicist explained that calculating the sound intensity required finding the common logarithm of the pressure ratio."
A logbook, or journal of a vessel (or aircraft)'s progress
A Hebrew unit of liquid volume (about ¹⁄₃ liter).
logarithm.
In plain English: A log is a piece of wood that has been cut from a tree and usually left with its bark on.
"He cut a heavy log from the firewood pile to warm the house."
Usage: Do not confuse the common noun "log" (a piece of wood) with the mathematical term "logarithm." Use "log" only when referring to a section of timber or a written record, never for calculating exponents.
enter into a log, as on ships and planes
"The captain ordered the officer to carefully log every deviation from the flight path during the stormy approach."
To cut trees into logs.
"The old wooden dock began to log in the gentle waves, sending a rhythmic creak through the air."
To make, to add an entry (or more) in a log or logbook.
To move to and fro; to rock.
In plain English: To log means to write down information or record an event for later reference.
"I logged my daily exercise hours in the app."
Usage: Do not use "log" as a verb to describe moving back and forth or rocking, as this is an incorrect usage. Instead, use it only to mean recording information in a journal or cutting down trees.
The word "log" likely comes from Old Norse lóg, meaning a felled tree that lies on the ground. It entered English via Middle English forms of uncertain origin, possibly traveling with merchants involved in the timber trade.