auto- 1
a combining form meaning "self," "same," "spontaneous," used in the formation of compound words: autograph. Also, esp. before a vowel, aut- .
[ autós self ]
auto- 2
a combining form representing automobile in compound words: autocade.
[ see AUTO ]
auto- 3
a combining form representing automatic in compound words: autoalarm; autofeed; autofocus. Sometimes also taken as an adjective: auto enlarger; auto stop control.