kōng​kōng

empty

空空 kōng​kōng
empty descriptive
containing nothing; vacant, hollow, or vacuous

Despite working for a long time, his pockets were still empty.

air-to-air place word
referring to missiles launched from an aircraft against another aircraft

This fighter jet is equipped with state-of-the-at air-to-air missiles.

Frequency

Movie subtitles
1.46 per million appears in 1% of films
Written text
4.38 per million

Sources

Definitions
CC-CEDICT