- null matrix
- null method
- null model
- null morphism
- null mutation
- null object
- null object of a category
- null-pair
- null path
- null plane
- null point
- null polarity
- null polynomial
- null-property
- null ray
- null-recurrent
- null-recurrent point
- null recurrent state
- null-recurrent state
- null relation
- null representation
- null representation module
- null-ring
- null row
- null sequence