回空

to return empty (i.e. to drive back with no passengers or freight)

to circle / to go back / to turn around / to answer / to return / to revolve / Hui ethnic group (Chinese Muslims) / time / classifier for acts of a play / section or chapter (of a classic book)

to curve / to return / to revolve

variant of 迴|回[hui2]

empty / air / sky / in vain

to empty / vacant / unoccupied / space / leisure / free time