The state of being null, or void, or invalid.
The difference between the rank of a matrix and the number of columns it has; the dimension of the nullspace of a matrix.
A void act; a defective proceeding or one expressly declared by statute to be a nullity.
Empty space.
An available room in a hotel; guest house, etc.
An unoccupied position or job.
Lack of intelligence or understanding.
A blank mind, unoccupied with thought.
A defect in a crystal caused by the absence of an atom in a lattice