kōng​zhōng​lóu​gé

unrealistic

空中楼阁 (空中樓閣) kōng​zhōng​lóu​gé
unrealistic expression
something that lacks a solid foundation, such as an unrealistic plan, an unfounded theory, or a castle in the air

Frequency

Movie subtitles
0.120 per million appears in 0% of films
Written text
0.587 per million

Sources

Definitions
CC-CEDICT