The kitchen is downstairs.

In a lower level of a building or structure.
She went downstairs to grab a snack.
The living room is located downstairs.
He heard a noise coming from downstairs.
go downstairs
come downstairs
stay downstairs
below
down
under
She went downstairs to grab a snack.

In a lower part of a building or structure.
He ran downstairs to answer the phone.
The kids are playing downstairs.
Please come downstairs for dinner.
go downstairs
come downstairs
sit downstairs
below
down
under
I went downstairs to get a snack.

In or to a lower floor of a building.
She went downstairs to answer the phone.
The kids are playing downstairs in the living room.
I found my keys downstairs by the front door.
go downstairs
come downstairs
stay downstairs
down
below
beneath