1.
floors, stories (of a building)
A counter for floors or stories of a building.
階 is the counter for building floors and stories.
IRREGULAR READINGS:
- 一階: first floor (with っ)
- 三階: third floor (voiced が)
- 何階: what floor? (voiced が)
COUNTING:
- 二階, 四階, 五階, 六階, 七階, 八階/八階, 九階, 十階
JAPANESE VS. BRITISH ENGLISH:
The first floor in Japan (一階) corresponds to the ground floor in British English. There is no separate 'ground floor' and 'first floor' distinction as in British usage.