空口

incomplete meal of a single dish / meat or vegetable dish without rice or wine / rice without meat or vegetables

empty / air / sky / in vain

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

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

mere verbal statement cannot be taken as proof (idiom)

empty promises

to make empty promises