Vacuum; a space containing nothing at all
An unoccupied space where something may be stored
A feeling of longing for someone or something that is gone; a sense of a thing's absence.
An unoccupied area or volume.
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.