(geometry) Having zero dimensions; having no extent in any direction.

The start of the first hour of the day on the 24-hour clock, i.e. 0:00, military time.

a very pure form of crystalline silicon, made by vertical zone melting

(military) The location of the center of a burst of a nuclear weapon at the instant of detonation. The zero point may be in the air, or on or beneath the surface of land or water, depending upon the type of burst, and it is thus to be distinguished from ground zero.

(military) An area into which a designated ground unit or fire support ship delivers, or is prepared to deliver, fire support. Fire may or may not be observed.

(military) A tactical subdivision of a larger area, the responsibility for which is assigned to a tactical unit; generally applied to offensive action.

(military) A technique in which the first motion of the missile or aircraft removes it from the launcher. Normally, such a launch occurs before the missile fuel or aircraft engine is fired.

(physics) associated with zero on any scale, but particularly with a temperature of absolute zero

(military) Rear part of a theater of war or theater of operations (behind but contiguous to the combat zone) which contains the lines of communications, establishments for supply and evacuation, and other agencies required for the immediate support and maintenance of the field forces. Also called COMMZ.

(Hebrew) Of blessed memory, may he/she/they rest in peace; used after a reference to one or more people who died.