Definition of automatic transmission
: a system in a vehicle that changes gears at different speeds without direct control by the driver I can't drive her car because it has a manual transmission instead of an automatic transmission.
Word by Word Definitions
: largely or wholly involuntary
: acting or done spontaneously or unconsciously
: a machine or apparatus that operates automatically
: an automatic firearm
: an automatic transmission
Seen and Heard
What made you want to look up automatic transmission? Please tell us where you read or heard it (including the quote, if possible).