log in

Collins Concise English Dictionary © HarperCollins Publishers::

log in verb

1. Also: log on to enter (an identification number, password, etc) from a remote terminal to gain access to a multiaccess system

noun

1. Also: login the process by which a computer user logs in

WordReference Random House Learner's Dictionary of American English © 2026

log¹ /lɔg, lɑg/   n., v., logged, log•ging. 
n. [countable]

1. a portion or length of the trunk or of a large limb of a tree that has fallen.
2. any detailed, usually sequential record, as of the progress of an activity or of the trip of a ship or aircraft.

v. 

3. [~ + object] to cut (trees) into logs.
4. to cut down the trees or timber on (land): [~ + object]
   logging the mountain behind our house.
   [no object]
   They have logged in that area for generations.
5. to enter in a log;
   compile:
   [~ + object] The captain logged the ship's position.
6. Aeronautics to travel at or for (a certain speed, time, or distance):
   [~ + object] logged 10,000 hours flying time.
7. log in or on, [no object] to gain access to a secured computer system or on-line service by keying in personal identification information.
8. Computing log off or out, to terminate a session on such a system or service: [no object]
   He logs off at night.
   [~ + object]
   He logged off the system.

log•ger, n. [countable]

log² /lɔg, lɑg/   n. 

1. Mathematics logarithm.

-log-, root. 

1. -log- comes from Greek, where it has the meaning "speak;
   word;
   speech.'' This meaning is found in such words as: analog, apology, chronology, decalogue, dialogue, doxology, epilogue, eulogy, ideology, logarithm, logic, logo, monologue, neologism, philology, syllogism, tautology, terminology.

See -logy.

WordReference Random House Unabridged Dictionary of American English © 2026

log¹  (lôg, log), n., v., logged, log•ging. 
n. 

1. a portion or length of the trunk or of a large limb of a felled tree.
2. something inert, heavy, or not sentient.
3. Nautical, Naval Terms any of various devices for determining the speed of a ship, as a chip log or patent log.
4. Aeronautics, Nautical, Naval Terms any of various records, made in rough or finished form, concerning a trip made by a ship or aircraft and dealing with particulars of navigation, weather, engine performance, discipline, and other pertinent details;
   logbook.
5. [Motion Pictures.] an account describing or denoting each shot as it is taken, written down during production and referred to in editing the film.
6. Mechanical Engineering a register of the operation of a machine.
7. Geology, Mining Also called well log. a record kept during the drilling of a well, esp. of the geological formations penetrated.
8. Computing any of various chronological records made concerning the use of a computer system, the changes made to data, etc.
9. Show Business [Radio and Television.] a written account of everything transmitted by a station or network.
10. British Terms Also called log of wood. [Australian Slang.] a lazy, dull-witted person;
    fool.

v.t. 

11. to cut (trees) into logs:
    to log pine trees for fuel.
12. to cut down the trees or timber on (land):
    We logged the entire area in a week.
13. to enter in a log;
    compile;
    amass;
    keep a record of:
    to log a day's events.
14. Aeronautics to make (a certain speed), as a ship or airplane:
    We are logging 18 knots.
15. Transport to travel for (a certain distance or a certain amount of time), according to the record of a log:
    We logged 30 miles the first day. He has logged 10,000 hours flying time.

v.i. 

16. to cut down trees and get out logs from the forest for timber:
    to log for a living.
17. Computing log in:
    • Also, log on, sign on. [Computers.] to enter identifying data, as a name or password, into a multiuser system, so as to be able to do work with the system.
    • to enter or include any item of information or data in a record, account, etc.
18. Computing log off or out, to terminate a work session using a multiuser system, or a connection to such a system.

• 1350–1400; Middle English logge, variant of lugge pole, limb of tree; compare obsolete logget pole; see lugsail, logbook

log′gish, adj. 

log²  (lôg, log), n. 

1. Mathematics logarithm.

log-, 

1. var. of logo- before a vowel:
   logarithm.

-log, 

1. var. of -logue:
   analog.

log., 

1. logic.