Of no legal or binding force or validity; of no efficacy; invalid; void; nugatory; useless.

Having a value of zero; as, of null utility.

Empty; having no members; as, the null set.

Unassigned or meaningless; -- a special value given to variables, especially pointers or logical variables, indicating that it is meaningless and cannot be used in computation; as, an uninitialized pointer in "C" is given a null value. The actual value that is stored in memory to indicate the null condition may vary with the computer language used.

In the C and C++ languages, a pointer that does not point to a data object. IBM. The pointer can be converted to any pointer type.

the C and C++ standard constant used to indicate that a pointer does not contain an address. In tests this value is converted to the boolean false. It is often used as a sentinel indicating the end of a linked data structure.

reference (pointer) to a null object

In the C language and in the Distributed Computing Environment (DCE), a pointer guaranteed not to point to a data object.

A point of minimum or no detection. Also see Lobing.

A low or minimum point on a graph. A minimum pressure region in a room.

A condition, such as balance, which results in a minimum absolute value of output.

On a polar-coordinate graph, the area that represents minimum or 0 radiation.

a place where there is very little or no signal. Also refers to the direction that a radio faces where it is getting much less signal from a station. With AM signals, you can get a station with the radio turned a certain way and yet when you turn it 90 degrees perpendicular from that position, you may actually lose the station altogether. This is that station's null.

a direction where a plane wave from that direction will be canceled

the compass point at which a radio direction finder's directional antenna receives the weakest signal from a given RDF station, thereby indicating the station's bearing.

In radio electronics, a null is an area or vector at which the signal from two or more of the antenna elements in an antenna system cancels out almost entirely.