"Ceiling zero" is a term used in aviation to describe the lowest altitude at which a pilot can fly due to poor visibility. Antonyms for this term include "unlimited ceiling," which refers to clear visibility and freedom to fly at any altitude without risk, and "high ceiling," which denotes a high level of visibility and the ability to fly at higher altitudes. Other antonyms for "ceiling zero" may include "clear sky," "unrestricted airspace," and "high altitude." These antonyms represent optimal conditions for flying, with no limitations imposed by weather or visibility factors. Thus, while "ceiling zero" denotes danger and restriction, the antonyms convey a sense of freedom and opportunity in the skies.