auto-1

1.
a combining form meaning “self,” “same,” “spontaneous,” used in the formation of compound words:
autograph, autodidact.
Also, especially before a vowel, aut-.
Origin
< Greek, combining form of autós self

auto-2

1.
a combining form representing automobile in compound words:
autocade.
Origin
see auto

auto-3

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.
British Dictionary definitions for auto-

auto-

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
Word Origin
from Greek autos self
Word Origin and History for auto-

word-forming element meaning "self, one's own, by oneself," from Greek auto- "self, one's own," combining form of autos "self, same," of unknown origin. Before a vowel, aut-; before an aspirate, auth-. In Greek also used as a prefix to proper names, e.g. automelinna "Melinna herself." The opposite prefix would be allo-.

auto- in Medicine

auto- or aut-
pref.
Self; same: autogamy.

auto- in Science
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.