a Tibetan utopia in James Hilton’s novel Lost Horizon (1933).
(as noun a Shangri-La) a place regarded as an earthly paradise, especially when involving a retreat from the pressures of modern civilization:we moved out of Los Angeles and created this mountain-top Shangri-La
from Shangri (an invented name) + Tibetan la 'mountain pass'
Shangri-La in other Oxford dictionaries
Definition of Shangri-La in the US English dictionary