door opener

Short definition from Wiktionary

Noun

1. 1
   The control mechanism by which a door is latched and unlatched.
2. 2
   Any of various devices designed to make opening a door easier.
3. 3
   Any of various devices designed to make opening a door easier: Any of various devices to automatically open a door in response to a sensor or signal sent from a controller.
4. 4
   Any of various devices designed to make opening a door easier: A crowbar-like tool used by firefighters to quickly force locked doors to open.
5. 5
   Someone who opens doors.
6. 6
   Any tactic, approach, or giveaway item employed by a salesman to capture the interest of a potential customer.
7. 7
   A communication technique designed to encourage someone to speak openly.
8. 8
   Someone or something that provides someone with opportunities that would otherwise be unavailable to them.