automatic
US /ˌɑː.t̬əˈmæt̬.ɪk/
UK /ˌɑː.t̬əˈmæt̬.ɪk/

1.
working by itself with little or no direct human control
:
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The car has an automatic transmission.
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The lights are on an automatic timer.
2.
done without conscious thought or intention; instinctive
:
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It was an automatic reaction to the sudden noise.
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Breathing is an automatic bodily function.
1.
a firearm that fires repeatedly as long as the trigger is pressed
:
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He carried an automatic rifle.
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The police seized several automatics during the raid.
2.
a car with automatic transmission
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I prefer driving an automatic over a manual.
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She just bought a new automatic.