a person or thing that dims.
Also called dimmer switch. a rheostat or similar device by which the intensity of an electric light may be varied.
  1. the low-beam headlights of an automobile or truck.
  2. the small, parking lights of an automobile.

Nearby words

  1. dimitrov,
  2. dimitrov, georgi,
  3. dimitrovo,
  4. dimity,
  5. dimly,
  6. dimorph,
  7. dimorphism,
  8. dimorphite,
  9. dimorphous,
  10. dimp

Origin of dimmer

First recorded in 1815–25; dim + -er1



adjective, dim·mer, dim·mest.

not bright; obscure from lack of light or emitted light: a dim room; a dim flashlight.
not seen clearly or in detail; indistinct: a dim object in the distance.
not clear to the mind; vague: a dim idea.
not brilliant; dull in luster: a dim color.
not clear or distinct to the senses; faint: a dim sound.
not seeing clearly: eyes dim with tears.
tending to be unfavorable; not likely to happen, succeed, be favorable, etc.: a dim chance of winning.
not understanding clearly.
rather stupid; dim-witted.

verb (used with object), dimmed, dim·ming.

to make dim or dimmer.
to switch (the headlights of a vehicle) from the high to the low beam.

verb (used without object), dimmed, dim·ming.

to become or grow dim or dimmer.

Verb Phrases

dim out, (in wartime) to reduce the night illumination of (a city, ship, etc.) to make it less visible from the air or sea, as a protection from enemy aircraft or ships.

Origin of dim

before 1000; Middle English, Old English dim(me), cognate with Old Frisian dim, Old Norse dimmr

Related forms

Synonym study

1. See dark.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for dimmer

British Dictionary definitions for dimmer



a device, such as a rheostat, for varying the current through an electric light and thus changing the illumination
(often plural) US
  1. a dipped headlight on a road vehicle
  2. a parking light on a car


adjective dimmer or dimmest

badly illuminateda dim room
not clearly seen; indistinct; fainta dim shape
having weak or indistinct visioneyes dim with tears
lacking in understanding; mentally dull
not clear in the mind; obscurea dim memory
lacking in brilliance, brightness, or lustrea dim colour
tending to be unfavourable; gloomy or disapproving (esp in the phrase take a dim view)

verb dims, dimming or dimmed

to become or cause to become dim
(tr) to cause to seem less bright, as by comparison
US and Canadian (tr) to switch (car headlights) from the main to the lower beamAlso called (in Britain and certain other countries): dip
Derived Formsdimly, adverbdimness, noun

Word Origin for dim

Old English dimm; related to Old Norse dimmr gloomy, dark

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for dimmer
Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with dimmer


see take a dim view.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.