piano nobile
Concise Oxford English Dictionary © 2008 Oxford University Press:
piano nobile /ˌpjɑːnəʊ ˈnəʊbɪleɪ/
▶noun Architecture the main storey of a large house, usually the first floor.
– origin Ital., lit. ‘noble floor’.
'piano nobile' also found in these Oxford entries:

