Fob/fɑːb/ Definition 1 of 3Pro Tip 1/3Technology Item Often refers to electronic devices used for accessing cars or buildings without a key. She clicked the fob to unlock her car. Pro Tip 2/3Keyring Addition Usually attached to a keyring for convenience and often decorative. His fob had a mini flashlight attached. Pro Tip 3/3Not Always Electronic Can also be a simple emblem or charm, not just an electronic device. Her fob was a small plastic mascot.