1. without conscious thought or effort; as a natural reaction
2. by means of a machine or system that operates without human control
3. as a necessary result; inevitably

Examples

• She automatically reached for her phone when it buzzed.
• The doors open automatically when you approach.
• The car’s lights turn on automatically at dusk.
• He automatically assumed she was right.
• The backup system starts automatically if the main one fails.
• Students who fail the test automatically have to retake it.
• The sprinkler system activates automatically during a fire.