floor; storey
Refers to a level or storey of a building. Often used as a suffix after a number or descriptor, e.g. 二階 (second floor).
This building is five storeys tall.
The reception desk is on the second floor.
Rare standalone noun for stairs; the reading きざはし is more common for this meaning. Modern Japanese usually uses 階段 (かいだん).
See also: 階 (きざはし)
In old texts, 階 can be read as きざはし and refer to stairs.
Technical term in chronostratigraphy for a stage, a unit of geological time. Not used in everyday conversation.
This fossil is from the Albian stage of the Cretaceous period.
counter for floors
Counter used for storeys or floors of a building. Attaches to numbers: 一階 (first floor), 何階 (which floor?).
This department store has floors from the second basement to the eighth floor.
This apartment building has ten floors.
I went up to the fifth floor by elevator.
The bookstore is on the third floor of the department store.
Excuse me, what floor is the restroom on?