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• auto
  auto

  noun

  automobile.
• auto-
  auto-

  a combining form meaning “self,” “same,” “spontaneous,” used in the formation of compound words.
• auto.
  auto.

  abbreviation

  automatic.

auto

¹ American  

[aw-toh] / ˈɔ toʊ /

noun

plural

autos

1. automobile.

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adjective

1. of or relating to automobiles.

   an auto salesman; auto detailing.

auto- ² American  

1. a combining form meaning “self,” “same,” “spontaneous,” used in the formation of compound words.

   autograph, autodidact.

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auto- ³ American  

1. a combining form representing automobile in compound words.

   autocade.

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auto- ⁴ American  

1. a combining form representing automatic in compound words: autoalarm; autofeed; autofocus . Sometimes also taken as an adjective.

   auto enlarger; auto stop control; auto dialer.

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auto. ⁵ American  

abbreviation

1. automatic.

2. automobile.

3. automotive.

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auto ¹ British  

/ ˈɔːtəʊ /

noun

1. 1. short for automobile

   2. ( as modifier )

      auto parts

2. informal short for autorickshaw

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auto- ² British  

combining form

1. self; same; of or by the same one

   autobiography

2. acting from or occurring within; self-caused

   autohypnosis

3. self-propelling; automatic

   automobile

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Etymology

Origin of auto¹

An Americanism dating back to 1895–1900; by shortening

Origin of auto-²

< Greek, combining form of autós self

Origin of auto-³

see origin at auto

Explanation

An auto is a car. If you drive your auto too fast, you might get a speeding ticket. The word auto is an informal, shortened form of automobile. You're most likely to hear the word auto when someone's talking about insurance, auto parts, or the auto industry. Automobile was originally a French word, formed from the Greek autos, or "self," and the French mobile, "moving."

Example Sentences

An epidemic of car break-ins led owners to post “No Radio” signs in their windows, and auto alarms blared indignantly at all hours.

From The Wall Street Journal • May 8, 2026

If you’re designing a chip for an auto, the design process is lengthy.

From Barron's • May 7, 2026

Police are asking auto repair shops to contact detectives if anyone recently brought in a sedan matching the description of the suspect’s vehicle.

From Los Angeles Times • May 7, 2026

Once you get onto the platform, you’re going to be designed into that auto for a number of years.

From Barron's • May 7, 2026

“He’s very nice. There’s a new kind of operation they’ll be doing on his eyes. He was in an auto accident, and his mother was killed.”

From "The Chosen" by Chaim Potok

Related Words

• car
• passenger car
• vehicle