[ aw-toh ]
/ ˈɔ toʊ /

noun, plural au·tos.


of or relating to automobiles: an auto salesman; auto detailing.

Origin of auto

An Americanism dating back to 1895–1900; by shortening

Definition for auto (2 of 5)


a combining form meaning “self,” “same,” “spontaneous,” used in the formation of compound words: autograph, autodidact.
Also especially before a vowel, aut- .

Origin of auto-

<Greek, combining form of autós self

Definition for auto (3 of 5)


a combining form representing automobile in compound words: autocade.

Origin of auto-

see origin at auto

Definition for auto (4 of 5)


a combining form representing automatic in compound words: autoalarm; autofeed; autofocus. Sometimes also taken as an adjective: auto enlarger; auto stop control; auto dialer.

Definition for auto (5 of 5)


automotive. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for auto

British Dictionary definitions for auto (1 of 2)

/ (ˈɔːtəʊ) /

noun plural -tos US and Canadian informal

  1. short for automobile
  2. (as modifier)auto parts
Indian informal short for autorickshaw

British Dictionary definitions for auto (2 of 2)


sometimes before a vowel aut-

combining form

self; same; of or by the same oneautobiography
acting from or occurring within; self-causedautohypnosis
self-propelling; automaticautomobile

Word Origin for auto-

from Greek autos self
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

Medical definitions for auto



Self; same:autogamy.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for auto


A prefix meaning “oneself,” as in autoimmune, producing antibodies or immunity against oneself. It also means “by itself, automatic,” as in autonomic, governing by itself.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.