Noun back door has 2 senses

1. back door - a secret or underhand means of access (to a place or a position); "he got his job through the back door"
   --₁ is a kind of access
   
2. back door, back entrance - an entrance at the rear of a building
   --₂ is a kind of exterior door, outside door
   

back door

Noun (Senses):

1. A door at the rear of a building or house.
2. A hidden or secret entrance.
3. An alternative route or means of access.
4. An illicit or covert method.

Sample Sentences:
1. The delivery person knocked on the back door.
2. The thieves entered through the back door to avoid security cameras.
3. Taking the back door allowed us to bypass the main entrance traffic.
4. Corruption often finds its way through the back door.

Adjective:

1. Relating to unofficial, clandestine, or secretive activities.

Sample Sentences:
1. He managed to gain back door access to classified information.
2. The company used back door negotiations to secure the deal.

Related Products:
- Back door locks
- Back door cameras
- Back door security systems