patio door 
noun
A large glass sliding door leading to a patio, garden, or balcony.There are loft-style high ceilings as well as large glass windows incorporating a patio door to a balcony....
- Additional features include understairs storage with shelving and a sliding patio door to the garden.
- Beside it the dining room is also a good size and includes more cornicing and a sliding patio door to the rear garden.