Of atmospheric conditions: characterized by or having both a zero cloud ceiling and zero (horizontal and vertical) visibility; (of a landing or other manoeuvre) carried out in such conditions. Also: designating visibility which is effectively zero in both horizontal and vertical directions.
2Designating an ejection seat that can eject a person safely even when the aircraft is on the ground and stationary (i.e. at zero altitude and zero velocity).
3Designating a disarmament proposal for the total removal of certain types of weapons on both sides of a conflict or confrontation; specifically one put forward in the early 1980s for both the Soviet Union and the United States to remove all their medium-range nuclear missiles from Europe. Especially in "zero-zero option", "zero-zero solution".
Atmospheric conditions in which both the (horizontal and vertical) visibility and the cloud ceiling are effectively zero.
2A zero-zero disarmament proposal or option.
1930s; earliest use found in Greeley (Colorado) Daily Tribune. From zero + zero.