- improper maximum
- improper minimum
- improper motion
- improper movement
- improper multiple integral
- improper node
- improper notation
- improper number
- improper orthogonal mapping
- improper orthogonal matrix
- improper orthogonal transformation
- improper partial graph
- improper plane
- improper point
- improper principal ordinal
- improper quadric
- improper quotient object
- improper rational function
- improper refinement
- improper representation
- improper rotation
- improper rotation group
- improper set
- improper singularity
- improper subalgebra